NCERT Solutions For Class 12 Physics Chapter 1 Electric Charges and Fields: Welcome to the updated NCERT book solutions for the very first chapter of the Class 12 syllabus. On this Careers360 page, you will find comprehensive electric charges and fields class 12 NCERT solutions covering questions from 1.1 to 1.34. Questions 1.1 to 1.23 belong to the exercise section, while questions 1.24 to 1.34 are part of the additional exercise. These class 12 physics ch1 NCERT solutions, crafted by subject experts, are presented in a simple and detailed manner. You can download the PDF for free and use them at your convenience.

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NCERT Solutions for Class 12 Physics Chapter 1 Electric Charges and Fields

Problems in Physics Class 12 Chapter 1 are important from the CBSE class 12 exam point of view. Try solving all the questions of NCERT Class 12 Physics Chapter 1 and if any doubt arises then check the CBSE NCERT solutions for Class 12 Physics Chapter 1 Electric Charges and Fields. Electrostatics is the study of electric charges at rest. The NCERT Class 12th Physics Electric Charges and Fields deal with the charging of a body, properties of charge, Columbus law, electric field, electric flux, Gauss law and application of Gauss law. Two main laws discussed in Physics Class 12 Chapter 1 are Gauss law and Columbus law. NCERT Solutions for Class 12 physics chapter 1 Electric Charges and Fields explains problems related to these topics.

The derivations in Physics Class 12 NCERT Chapter 1 Electric Charges and Fields of NCERT are very important in CBSE board exam point of view. As the second chapter of NCERT solutions for Class 12 is the continuation of the NCERT Class 12 Physics chapter 1 pdf, it is important to remember all points studied in the chapter. These class 12 electric field and charges ncert solutions will help you in a better understanding of the concepts you have studied. While studying NCERT Solutions for Class 12 Physics Chapter 1 formulas can be compared with the chapter Gravitation of Physics NCERT solutions class 11.

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NCERT Solutions for Class 12 Physics Chapter 1 Electric Charges and Fields

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NCERT Solutions for Class 12 Physics Chapter 1 Electric Charges and Fields: Exercise Question Answer

Q 1.1 What is the force between two small charged spheres having charges of $2 \times 10^{-7}$ C and $3 \times 10^{-7}C$ placed 30 cm apart in air?

Answer:

Given,

$q_{1}$ = $2 \times 10^{-7}$ C

$q_{2}$ = $3 \times 10^{-7}C$

r = 30 cm = 0.3 m

We know,

Force between two charged particles, $q_{1}$ and $q_{2}$ separated by a distance r.

$F = \frac{1}{4\pi \epsilon _{0}} \frac{q_{1}q_{2}}{r^2}$

$= \frac{1}{4\pi \epsilon _{0}} \frac{2\times10^{-7} \times 3 \times 10^{-7}}{(30\times10^{-2}\ m)^2\ }$

$= (9\times10^9\ N)\times \frac{6\times10^{-14+4}}{900\ m^2\ } = 6\times10^{-3} N$

Since the charges are of the same nature, the force is repulsive.

Q 1.2 (a) The electrostatic force on a small sphere of charge $0.4 \mu C$ due to another small sphere of charge $-0.8 \mu C$ in air is $-0.2N$ . (a) What is the distance between the two spheres?

Answer:

Given,

$q_{1}$ = $0.4 \mu C$

$q_{2}$ = $-0.8 \mu C$

F = $-0.2N$ (Attractive)

We know,

Force between two charged particles, $q_{1}$ and $q_{2}$ separated by a distance r.

$F = \frac{1}{4\pi \epsilon _{0}} \frac{q_{1}q_{2}}{r^2}$

$\\ -0.2 = 9\times10^9 \times \frac{(0.4\times10^{-6})(-0.8\times10^{-6})}{r^2} \\ \implies r^2 = 9\times10^9\times0.32\times10^{-12}/0.2 \\ \implies r^2 = 9\times0.16\times10^{-2} \\ \implies r = 1.2\times10^{-1} m = 0.12 m =12 cm$

Therefore, the distance between the two charged spheres is 12 cm.

Q 1.2(b) The electrostatic force on a small sphere of charge $0.4 \mu C$ due to another small sphere of charge $-0.8 \mu C$ in air is $0.2N$ .(b)What is the force on the second sphere due to the first?

Answer:

Using Newton's third law, the force exerted by the spheres on each other will be equal in magnitude.

Therefore, the force on the second sphere due to the first = 0.2 N (This force will be attractive since charges are of opposite sign.)

Q 1.3 Check that the ratio $\frac{ke^{2}}{Gm_{e}m_{p}}$ is dimensionless. Look up a Table of Physical Constants and determine the value of this ratio. What does the ratio signify?

Answer:

Electrostatic force

$F=\frac{KQ^2}{r^2}$

So the dimension of

$[Ke^2]=[Fr^2]$ ..................(1)

The gravitational force between two bodies of mass M and m is

$F=\frac{GMm}{r^2}$

so dimension of

$[Gm_em_p]=[Fr^2]$ .............(2)

Therefore from (1) and (2)

$[\frac{ke^{2}}{Gm_{e}m_{p}} ]$ is dimensionless

Here,

K = $1/4\pi \epsilon _{0}$ , where is the permittivity of space. $[1/ \epsilon _{0}] =[C/V.m] = [Nm^2 C^{-2}]$

e = Electric charge ([e] = [C])

G = Gravitational constant. ([G]= $[Nm^2kg^{-2}]$ )

$m_{e}$ and $m_{p}$ are mass of electron and proton ([ $m_{e}$ ] = [ $m_{p}$ ] = [Kg])

Substituting these units, we get

$[\frac{ke^{2}}{Gm_{e}m_{p}} ] = [\frac{C^2 \times Nm^2C^{-2}}{Nm^2kg^{-2}\times kg\times kg} ] = M^{0}L^{0}T^{0}$

Hence, this ratio is dimensionless.

Putting the value of the constants

$\frac{ke^{2}}{Gm_{e}m_{p}} = \frac{9\times10^9\times(1.6\times10^{-19})^{2}}{6.67\times10^{11}\times9.1\times10^{-31}\times1.67\times10^{-27}}$

$=2.3 \times 10^{40}$

The given ratio is the ratio of electric force $\frac{ke^{2}}{R^2}$ to the gravitational force between an electron and a proton $\frac{Gm_{e}m_{p}}{R^2}$ considering the distance between them is constant!

Q 1.4 (a) Explain the meaning of the statement ‘electric charge of a body is quantised’.

Answer:

The given statement "electric charge of a body is quantised" implies that charge on a body can take only integral values. In other words, only the integral number of electrons can be transferred from one body to another and not in fractions.

Therefore, a charged body can only have an integral multiple of the electric charge of an electron.

Q 1.4 (b) Why can one ignore quantisation of electric charge when dealing with macroscopic i.e., large scale charges?

Answer:

On a macroscopic level, the amount of charge transferred is very large as compared to the charge of a single electron. Therefore, we tend to ignore the quantisation of electric charge in these cases and considered to be continuous in nature.

Q 1.5 When a glass rod is rubbed with a silk cloth, charges appear on both. A similar phenomenon is observed with many other pairs of bodies. Explain how this observation is consistent with the law of conservation of charge.

Answer:

When a glass rod is rubbed with a silk cloth, opposite charges appear on both the rod and the cloth.

The phenomenon of charging bodies by rubbing them against each other is known as charging by friction. Here, electrons are transferred from one body to another giving both the bodies an equal but opposite charge. The number of electrons lost by one body (attains positive charge due to loss of negatively charged electrons) is equal to the number of electrons gained by the other body (attains negative charge). Therefore, the net charge of the system is zero. This is in accordance with the law of conservation of charge

Q 1.6 Four point charges $q_{A}= 2 \mu C$ , $q_{B}= -5 \mu C$ , $q_{C}= 2 \mu C$ , and $q_{D}= -5 \mu C$ are located at the corners of a square ABCD of side 10 cm. What is the force on a charge of 1 μC placed at the centre of the square?

Answer:

Charges at (A, C) and (B, D) are pairwise diametrically opposite and also equal.

Therefore, their force on a point charge at the centre of the square will be equal but opposite in directions.

Now, AC = BD = $\sqrt{2}\times(10\times10^{-2} m) = \sqrt{2}\times0.1 m$

$\therefore$ AO = BO = CO = DO = r = Half of diagonal = $\sqrt{2}\times0.05 m$

Force on point charge at centre due to charges at A and C = $F_{A} = -F_{C} = \frac{k(2\mu C)(1\mu C)}{(r)^2}$

Similarly, force on point charge at centre due to charges at B and D = $F_{B} = -F_{D} = \frac{k(-5\mu C)(1\mu C)}{(r)^2}$

$\therefore$ Net force on point charge = $\\F_{A} + F_{B} + F_{C} + F_{D} \\$

$= -F_{B} +F_{B} - F_{D} + F_{D} = 0$ .

Hence, the charge at the centre experiences no force.

Q 1.7 (a) An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why not?

Answer:

A positive point charge experiences a force in an electrostatic field. Since the charge will experience a continuous force and cannot jump from one point to another, the electric field lines must be continuous.

Q 1.7 (b) Explain why two field lines never cross each other at any point?

Answer:

A tangent drawn at any point on a field line gives the direction of force experienced by a unit positive charge due to the electric field on that point. If two lines intersect at a point, then the tangent drawn there will give two directions of force, which is not possible. Hence two field lines cannot cross each other at any point.

Q 1.8 (a) Two point charges $q_{A}=3 \mu C$ and $q_{B}=-3 \mu C$ are located 20 cm apart in vacuum. (a) What is the electric field at the midpoint O of the line AB joining the two charges?

Answer:

1643006219871

Given, AB = 20 cm

Since, O is the midpoint of the line AB.

AO = OB = 10 cm = 0.1m

The electric field at a point caused by charge q, is given as,

$E = \frac{kq}{r^2}$

Where, q is the charge, r is the distance between the charges and the point O

k = 9x10 ⁹ N m ² C ^-2

Now,

Due to charge at A, electric field at O will be $E_{A}$ and in the direction AO.

$E_{A} =\frac{ 9\times10^9 \times 3\times10^{-6}}{0.1^2}$

Similarly the electric field at O due to charge at B, also in the direction AO

$E_{B} =\frac{ 9\times10^9 \times (-3\times10^{-6})}{0.1^2}$

Since, both the forces are acting in the same direction, we can add their magnitudes to get the net electric field at O:

E' = $E_{A}$ + $E_{B}$ = 2E (Since their magnitudes are same)

$E' =2\times \frac{ 9\times10^9 \times 3\times10^{-6}}{0.1^2} = 5.4\times 10^4 N/C$ along the direction AO.

Q 1.8 (b) Two point charges $q_{A}=3\mu C$ and $q_{B}=-3\mu C$ are located 20 cm apart in vacuum. If a negative test charge of magnitude $1.5 \times 10^{-9}C$ is placed at this point, what is the force experienced by the test charge?

Answer:

Let Q = $-1.5 \times10^{-9}$ C

The force experienced by Q when placed at O due to the charges at A and B will be:

$F = Q \times E'$

where 'E' is the net electric field at point O.

$F=1.5 \times 10^{-9} C \times 5.4 \times 10^4 N/C = 8.1\times10^{-3 } N$

Q being negatively charged will be attracted by positive charge at A and repelled by negative charge at B. Hence the direction of force experienced by it will be in the direction of OA.

Q 1.9 A system has two charges $q_{A}=2.5\times 10^{-7}C$ and $q_{B}=-2.5\times 10^{-7}$ C located at points A: (0, 0, –15 cm) and B: (0,0, +15 cm), respectively. What are the total charge and electric dipole moment of the system?

Answer:

1643006161832 Given,

$q_{A}=2.5\times 10^{-7}C$ and $q_{B}=-2.5\times 10^{-7}$

The total charge of the system = $q_{A} + q_{B} = 0$

$\therefore$ The system is electrically neutral. (All dipole systems have net charge zero!)

Now, distance between the two charges, d = 15 + 15 = 30 cm = 0.3 m

We know, The electric dipole moment of the system, p = $q_{A}$ x d = $q_{B}$ x d (i.e, the magnitude of charge x distance between the two charges)

$\therefore p = 2.5\times10^{-7} C \times 0.3 m = 7.5\times10^{-8} Cm$

The direction of a dipole is towards the positive charge . Hence, in the positive z-direction.

Q 1.10 An electric dipole with dipole moment $4\times 10^{-9} Cm$ is aligned at $30^{\circ}$ with the direction of a uniform electric field of magnitude $5\times 10^{4}NC^{-1}$ . Calculate the magnitude of the torque acting on the dipole.

Answer:

1643006119102 Given,

Electric dipole moment, p = $4\times 10^{-9} Cm$

$\Theta = 30^{0} \ \therefore sin\Theta = 0.5$

E = $5\times 10^{4}NC^{-1}$

We know, the torque acting on a dipole is given by:

$\tau = p \times E$

$\implies \tau = p Esin\Theta = 4\times10^{-9} \times5\times10^{4}\times0.5 \ Nm$

$\implies \tau =10^{-4}Nm$

Therefore, the magnitude of torque acting on the dipole is $10^{-4}Nm$

Q 1.11 (a) A polythene piece rubbed with wool is found to have a negative charge of $3\times 10^{-7}$ . (a) Estimate the number of electrons transferred (from which to which?)

Answer:

Clearly, polyethene being negatively charged implies that it has an excess of electrons(which are negatively charged!). Therefore, electrons were transferred from wool to polyethene.

Given, charge attained by polyethene = $-3\times 10^{-7}$ C

We know, Charge on 1 electron = $-1.6\times10^{-19} C$

Therefore, the number of electrons transferred to attain a charge of $-3\times 10^{-7}$ =

$\frac{-3\times 10^{-7}}{-1.6\times10^{-19} C} = 1.8\times10^{12}$ electrons.

Q 1.11 (b) A polythene piece rubbed with wool is found to have a negative charge of $3\times 10^{-7}C$ . Is there a transfer of mass from wool to polythene?

Answer:

The charge attained by polyethene (and also wool!) is solely due to the transfer of free electrons.

We know, Mass of an electron = $9.1\times10^{-31}\ kg$

The total mass of electron transferred = number of electrons transferred x mass of an electron

= $9.1\times10^{-31} \times 1.8\times10^{12}\ kg = 16.4\times10^{-19} \ kg$

Yes, there is a transfer of mass but negligible.

Q 1.12 (a) Two insulated charged copper spheres A and B have their centres separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is $6.5\times 10^{-7}C$ ? The radii of A and B are negligible compared to the distance of separation.

Answer:

Since the radii of the spheres A and B are negligible compared to the distance of separation, we consider them as a point object.

Given,

charge on each of the spheres = $6.5\times 10^{-7}C$

and distance between them, r = 50 cm = 0.5 m

We know,

$F = k\frac{q_{1}q_{2}}{r^2}$

Therefore, the mutual force of electrostatic repulsion(since they have the same sign of charge)

$F = 9\times10^9Nm^{2}C^{-2}\times\frac{(6.5\times10^{-7}\ C)^2}{(0.5\ m )^2} = 1.5\times10^{-2} N$

Q 1.12 (b) What is the force of repulsion if each sphere is charged double the above amount, and the distance between them is halved?

Answer:

We know, force between two charged particles separated by a distance r is:

$F = k\frac{q_{1}q_{2}}{r^2} = k\frac{q^2}{r^2}$ $(\because q_{1} = q_{2} = q)$

Now if $q\rightarrow 2q\ and\ r\rightarrow r/2$

The new value of force:

$F_{new} =k\frac{(2q)^2}{(r/2)^2} = 16k\frac{q^2}{r^2} = 16F$

Therefore, the force increases 16 times!

$F_{new} =16F = 16\times1.5\times10^{-2} N = 0.24\ N$

Q 1.13 Suppose the spheres A and B in Exercise 1.12 have identical sizes. A third sphere of the same size but uncharged is brought in contact with the first, then brought in contact with the second, and finally removed from both. What is the new force of repulsion between A and B?

Answer:

When two spheres of the same size are touched, on attaining the equipotential state, the total charge of the system is equally distributed on both of them.

Therefore, (i) When uncharged third sphere C is touched with A, charge left on A = $0.5\times 6.5\times 10^{-7}C$

and charge attained by C = $0.5\times 6.5\times 10^{-7}C$

(ii) Now, charge on B + charge on C = $6.5\times 10^{-7}C$ + $0.5\times 6.5\times 10^{-7}C$ = $1.5\times 6.5\times 10^{-7}C$

When touched, charge left on B = $0.5\times1.5\times 6.5\times 10^{-7}C$

Therefore $q_{A}\rightarrow 0.5\times q_{A}\ and\ q_{B}\rightarrow 0.75\times q_{B}$

Therefore, $F' = 0.5\times0.75 \times F = 0.375 \times 1.5\times10^{-2} N = \boldsymbol{5.7\times10^{-3}\ N}$

Q 1.14 Figure shows tracks of three charged particles in a uniform electrostatic field. Give the signs of the three charges. Which particle has the highest charge to mass ratio?

1643006268513 Answer:

Charges 1 and 2 are repelled by the negatively charged plate of the system

Hence 1 and 2 are negatively charged .

Similarly, 3 being repelled by positive plate is positively charged.

(charge to the mass ratio: charge per unit mass)

Since 3 is deflected the most, it has the highest charge to mass ratio .

Q 1.15 (a) Consider a uniform electric field $E=3\times 10^{3}\ \widehat{i}\ N/C$ . (a) What is the flux of this field through a square of 10 cm on a side whose plane is parallel to the yz plane?

Answer:

Given,

$E=3\times 10^{3}\ \widehat{i}\ \frac{N}{C}$

Area of the square = $0.01^2\ m^2$

Since the square is parallel to the yz plane, therefore it's normal is in x-direction.(i.e $\widehat{i}$ direction )

therefore, flux through this surface:

$\phi = E.A$

$\implies \phi = (3\times10^3\ \widehat{i}).(0.01\ \widehat{i}) Nm^2/C = \boldsymbol{30 Nm^2/C}$

Q 1.15 (b) Consider a uniform electric field $E=3 \times 10^{3}\ \widehat{i}\ N/C$ .What is the flux through the same square if the normal to its plane makes a $60^{\circ}$ angle with the x-axis?

Answer:

Now, Since the normal of the square plane makes a $60^{\circ}$ angle with the x-axis

$cos\Theta = cos(60^{0}) = 0.5$

therefore, flux through this surface:

$\phi = E.A = EAcos\Theta$

$\implies \phi = (3\times10^3)(0.01)(0.5) Nm^2/C = \boldsymbol{15\ Nm^2/C}$

Q 1.16 What is the net flux of the uniform electric field of Exercise 1.15 through a cube of side 20 cm oriented so that its faces are parallel to the coordinate planes?

Answer:

The net flux of the uniform electric field through a cube oriented so that its faces are parallel to the coordinate planes is z ero .

This is because the number of lines entering the cube is the same as the number of lines leaving the cube.

Alternatively,

using Gauss’s law, we know that the flux of electric field through any closed surface S is $1/\epsilon _{0}$ times the total charge enclosed by S.

i.e. $\phi = q/\epsilon _{0}$

where, q = net charge enclosed and $\epsilon _{0}$ = permittivity of free space (constant)

Since there is no charge enclosed in the cube, hence $\phi = 0$ .

Q 1.17 (a) Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is $8.0 \times 10^{3}\frac{Nm^{2}}{C}$ . (a) What is the net charge inside the box?

Answer:

Using Gauss’s law, we know that the flux of electric field through any closed surface S is $1/\epsilon _{0}$ times the total charge enclosed by S.

i.e. $\phi = q/\epsilon _{0}$

where, q = net charge enclosed and $\epsilon _{0}$ = permittivity of free space (constant)

Given, $\phi = 8.0 \times10^3\ Nm^2/C$

$\therefore q = \phi \times\epsilon _{0} = (8.0\times10^3 \times8.85\times10^{-12})\ C$

$\implies q = 70 \times10^{-9} C = \boldsymbol{0.07 \mu C}$

This is the net charge inside the box.

Q 1.17 (b) Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is $8.0\times 10^{3}\frac{Nm^{2}}{C}$ .If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box? Why or Why not?

Answer:

Using Gauss's law, we know that $\phi = q/\epsilon _{0}$

Since flux is zero, q = 0, but this q is the net charge enclosed by the surface.

Hence, we can conclusively say that net charge is zero, but we cannot conclude that there are no charges inside the box.

Q 1.18 A point charge $+10 \mu C$ is a distance 5 cm directly above the centre of a square of side 10 cm, as shown in Fig. What is the magnitude of the electric flux through the square? (Hint: Think of the square as one face of a cube with edge 10 cm.)

esc1

Answer:

Let us assume that the charge is at the centre of the cube with edge 10 cm.

Using Gauss's law, we know that the flux of electric field through any closed surface S is $1/\epsilon _{0}$ times the total charge enclosed by S.

i.e. $\phi = q/\epsilon _{0}$

where, q = net charge enclosed and $\epsilon _{0}$ = permittivity of free space (constant)

Therefore, flux through the cube: $\phi = (10\times10^{-6} C)/\epsilon _{0}$

Due to symmetry, we can conclude that the flux through each side of the cube, $\phi'$ , will be equal.

$\therefore \phi' = \frac{\phi}{6} = \frac{10^{-5}}{6\times\epsilon _{0}} = \frac{10^{-5}}{6\times\ 8.85\times10^{-12}} = \boldsymbol{1.9 \times 10^5\ Nm^2C^{-1}}$

Q 1.19 A point charge of $2.0\mu C$ is at the centre of a cubic Gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?

Answer:

Given,

q = net charge inside the cube = $2.0\mu C$

Using Gauss’s law, we know that the flux of electric field through any closed surface S is $1/\epsilon _{0}$ times the total charge enclosed by S.

i.e. $\phi = q/\epsilon _{0}$

where, q = net charge enclosed and $\epsilon _{0}$ = permittivity of free space (constant)

$\therefore \phi = 2.0\times10^{-6}/8.85\times10^{-12}\ Nm^2C^{-1} = \boldsymbol{2.2\times10^5\ Nm^2C^{-1}}$

(Note: Using Gauss's formula, we see that the electric flux through the cube is independent of the position of the charge and dimension of the cube! )

Q 1.20 (a) A point charge causes an electric flux of $-1.0\times 10^{3}\frac{Nm^{2}}{C}$ to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge. If the radius of the Gaussian surface were doubled, how much flux would pass through the surface?

Answer:

Given,

$\phi = -1.0\times 10^{3}\frac{Nm^{2}}{C}$

Using Gauss’s law, we know that the flux of electric field through any closed surface S is $1/\epsilon _{0}$ times the total charge enclosed by S.

i.e. $\phi = q/\epsilon _{0}$

where, q = net charge enclosed and $\epsilon _{0}$ = permittivity of free space (constant)

Therefore, flux does not depend on the radius of the sphere but only on the net charge enclosed. Hence, the flux remains the same although the radius is doubled.

$\phi' = -10^{3}\frac{Nm^{2}}{C}$

Q 1.20 (b) A point charge causes an electric flux of $-1.0\times 10^{3}\frac{Nm^{2}}{C}$ to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge. What is the value of the point charge?

Answer:

Given,

$\phi = -1.0\times 10^{3}\frac{Nm^{2}}{C}$

Using Gauss’s law, we know that the flux of electric field through any closed surface S is $1/\epsilon _{0}$ times the total charge enclosed by S.

i.e. $\phi = q/\epsilon _{0}$

where, q = net charge enclosed and $\epsilon _{0}$ = permittivity of free space (constant)

$\therefore q = -10^{3}Nm^2C^{-1} \times 8.85\times10^{-12}N^{-1}m^{-2}C^{2} = -8.8\times10^{-9}\ C \\ = \boldsymbol{-8.8\ nC}$

Q 1.21 A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is $1.5 \times 10^{3}\frac{N}{C}$ and points radially inward, what is the net charge on the sphere?

Answer:

We know, for determining the electric field at r>R for a conducting sphere, the sphere can be considered as a point charge located at its centre.

Also, electric field intensity at a point P, located at a distance r, due to net charge q is given by,

$E = k\frac{q}{r^2}$

Given, r = 20 cm = 0.2 m (From the centre, not from the surface!)

$\\ \therefore 1.5\times10^3 = 9\times10^9\times \frac{q}{0.2^2} \\ \implies q = \frac{1.5\times0.04}{9}\times10^{-6} = 6.67\times10^{-9}\ C$

Therefore, charge on the conducting sphere is $- 6.67\ nC$ (since flux is inwards)

Q 1.22 (a) A uniformly charged conducting sphere of 2.4 m diameter has a surface charge density of $80.0\frac{\mu C}{m^{2}}$ . (a) Find the charge on the sphere.

Answer:

Given,

Surface charge density = $80.0\mu Cm^{-2}$

Diameter of sphere = 2.4 m $\therefore$ radius of sphere, r = 1.2 m

The charge on the sphere, Q= surface charge density x surface area of the sphere

$= (80\times10^{-6})\times(4\pi r^2) = 320\times22/7\times(1.2)^2 = \boldsymbol{1.45\times10^{-3}\ C}$

Q 1.22 (b) A uniformly charged conducting sphere of 2.4 m diameter has a surface charge density of $80.0 \frac{\mu C}{m^{2}}$ . (b) What is the total electric flux leaving the surface of the sphere?

Answer:

Using Gauss's law, we know that :

$\phi = q/ \epsilon_{0}$

$\implies \phi = 1.45\times10^{-3}/ 8.85\times10^{-12} = 1.6\times10^{8}\ Nm^2C^{-1}$

Q 1.23 An infinite line charge produces a field of $9\times 10^{4}\frac{N}{C}$ at a distance of 2 cm. Calculate the linear charge density.

Answer:

Given,

$\lambda = 9\times 10^{4}\frac{N}{C}$

d = 2 cm = 0.02 m

We know, For an infinite line charge having linear charge density $\lambda$ , the electric field at a distance d is:

$E = k\lambda / d$

$\therefore 9\times10^4 = 9\times10^{9}\lambda / 0.02$

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The linear charge density is $10 \mu C/cm$ .

Q 1.24 (a) Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude $17\times 10^{-22}\frac{C}{m^{2}}$ What is E: (a) in the outer region of the first plate

Answer:

We know, electric field, E, due to an infinite plate (length>>thickness) having surface charge density $\sigma$ = $\sigma/2\epsilon_{0}$ .

(To note: It's independent of distance from the plate!)

In the region outside the first plate,

since both plates have the same surface charge density(in magnitude only), their electric fields are same in magnitude in this region but opposite in direction.

(E due to positive plate away from it and E due to negative plate towards it!)

Hence, the electric field in the outer region of the first plate is zero.

Q 1.24 (b) Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude $17\times 10^{-22}\frac{C}{m^{2}}$ . What is E:(b) in the outer region of the second plate

Answer:

We know, electric field, E, due to an infinite plate (length>>thickness) having surface charge density $\sigma$ = $\sigma/2\epsilon_{0}$ .

(To note: It's independent of distance from the plate and same everywhere!)

In the region outside the second plate,

Since both plates have the same surface charge density(in magnitude only), their electric fields are same in magnitude in this region but opposite in direction.

(E due to positive plate away from it and E due to negative plate towards it!)

Hence, the electric field in the outer region of the second plate is zero.

Q 1.24 (c) Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude $17\times 10^{-22}\frac{C}{m^{2}}$ . What is E:(c) between the plates?

Answer:

We know, electric field, E, due to an infinite plate (length>>thickness) having surface charge density $\sigma$ = $\sigma/\epsilon_{0}$ .

(To note: It's independent of distance from the plate!)

Let A and B be the two plates such that:

$\sigma_{A}= 17\times10^{-22} Cm^{-2}$ = $\sigma$

$\sigma_{B}= -17\times10^{-22} Cm^{-2}$ = - $\sigma$

Therefore,

The electric field between the plates, E = $E_{A} + E_{B}$ = $\sigma_{A}/2\epsilon_{0} + (-\sigma_{B}/2\epsilon_{0})$

$= \sigma/2\epsilon_{0} = 17\times10^{-22}/8.85\times10^{-12} = 1.92\times10^{-10 } NC^{-1}$

NCERT Solutions for Class 12 Physics Chapter 1 Electric Charges and Fields: Additional Exercises Question

Q 1.25 An oil drop of 12 excess electrons is held stationary under a constant electric field of $2.55 \times 10^{4}NC^{-1}$ (Millikan’s oil drop experiment). The density of the oil is 1.26 g cm ^-3 . Estimate the radius of the drop.

Answer:

The force due to the electric field is balancing the weight of the oil droplet.

weight of the oil drop = density x volume of the droplet x g = $\rho \times \frac{4}{3}\pi r^3 \times g$

Force due to the electric field = E x q

charge on the droplet, q = No. of excess electrons x charge of an electron = $12\times q_{e} = 12\times 1.6\times10^{-19} = 1.92\times10^{-18} C$

Balancing forces:

$\rho \times \frac{4}{3}\pi r^3 \times g = E\times q$

Putting known and calculated values:

$\\ r^3 =\frac{3}{4\pi} E\times q / \rho\times g = \frac{3}{4}\times\frac{7}{22}\times(2.55\times10^4)\times 1.92\times10^{-18} / (1.26\times10^3 \times10 ) \\ = 0.927\times10^{-18} m^3$

$r = 0.975\times10^{-6} m = 9.75\times10^{-4} mm$

Q 1.26 Which among the curves shown in Figure cannot possibly represent electrostatic field lines?

esc12

1643005781117

Answer:

(a) Wrong, because field lines must be normal to a conductor.

(b) Wrong, because field lines can only start from a positive charge. It cannot start from a negative charge,

(d) Wrong, because field lines cannot intersect each other,

(e) Wrong, because electrostatic field lines cannot form closed loops.

Q 1.27 In a certain region of space, electric field is along the z-direction throughout. The magnitude of electric field is, however, not constant but increases uniformly along the positive z-direction, at the rate of $10^{5}NC^{-1}$ per metre. What are the force and torque experienced by a system having a total dipole moment equal to $10^{-7}$ Cm in the negative z-direction ?

Answer:

Force on a charge F=qE

but here E is varying along the Z direction.

Force can be written as,

$F=q\frac{dE}{dz}dz=P\frac{dE}{dz}=10^{-7}\times10^5=10^{-2}N$

Torque experienced =0 since both dipole and electric field are in the Z direction. The angle between dipole and the electric field is 180 degrees

$\tau = \mathbf{P}\times \mathbf{E}=PEsin\180=0$

Q 1.28 (a) A conductor A with a cavity as shown in Figure a is given a charge Q. Show that the entire charge must appear on the outer surface of the conductor.

1643005593691

Answer:

We know that the electric field inside a conductor is zero.

Using Gauss' law, if we draw any imaginary closed surface inside the solid, net charge must be zero.(Since E= 0 inside)

Hence there cannot be any charge inside the conductor and therefore, all charge must appear on the outer surface of the conductor.

Q 1.28 (b) Another conductor B with charge q is inserted into the cavity keeping B insulated from A. Show that the total charge on the outside surface of A is Q + q

1643005642848

Answer:

We know, electric field inside a conductor is zero.

Now, imagine a Gaussian surface just outside the cavity inside the conductor. Since, E=0 (Using Gauss' law), hence net charge must be zero inside the surface. Therefore, -q charge is induced on the inner side of the cavity(facing conductor B).

Now consider a Gaussian surface just outside the conductor A. The net electric field must be due to charge Q and q. Hence, q charge is induced on the outer surface of conductor A. Therefore, the net charge on the outer surface of A is Q + q.

Q 1.28 (c) A sensitive instrument is to be shielded from the strong electrostatic fields in its environment. Suggest a possible way.

1643005677851

Answer:

We know that the electric field inside a conductor is zero.

Therefore, a possible way to shield from the strong electrostatic fields in its environment is to enclose the instrument fully by a metallic surface.

Q 1.29 A hollow charged conductor has a tiny hole cut into its surface. Show that the electric field in the hole is $\left (\frac{\sigma}{2 \epsilon_{0}} \right )$ $\widehat{n}$ , where $\widehat{n}$ is the unit vector in the outward normal direction, and σ is the surface charge density near the hole.

Answer:

1643005712828

Let the surface area of the sphere be S.

And assume that the hole is filled. For a point B, just above the hole, considering a gaussian surface passing through B, we have

$\oint E.dS = q/\epsilon_{0}$

Now, since the electric field is always perpendicular to the surface of the conductor.

$\\ \therefore \oint E.dS = E.S= q/\epsilon_{0} = (\sigma.S)/\epsilon_{0} \\ \implies E = \sigma/\epsilon_{0}$

Using Superposition principle, $E =E_{1} + E_{2}$ ,

where $E_{1}$ is due to the hole and $E_{2}$ is due to the rest of the conductor. (both pointing outwards, i.e away from the centre)

Again, for a point A, just below the hole, Electric field will be zero because of electrostatic shielding.

Using the superposition principle, this will be due to $E_{1}$ pointing inwards(towards the centre) and due to $E_{2}$ (Pointing away from the centre)

$0 =E_{1}-E_{2}$ $\implies E_{1}=E_{2}$

Using this relation, we get:

$E =E_{1} + E_{2} = 2E_{1} \implies E_{1} = E/2 = \sigma/2\epsilon_{0}$

Since this is pointing outwards,

$\boldsymbol{E_{1}} = \sigma/2\epsilon_{0}\ \boldsymbol{\widehat{n}}$ is the electric field in the hole.

(Trick: 1. Assume the hole to be filled.

2. Consider 2 points just above and below the hole.

3. Electric fields at these points will be due to the hole and rest of the conductor. Use superposition principle.)

Q 1.30 Obtain the formula for the electric field due to a long thin wire of uniform linear charge density E without using Gauss’s law.

[Hint: Use Coulomb’s law directly and evaluate the necessary integral.]

Answer:

Let AB be a long thin wire of uniform linear charge density λ.

Let us consider the electric field intensity due to AB at point P at a distance h from it as shown in the figure.

1515132007897481

The charge on a small length dx on the line AB is q which is given as q = λdx.

So, according to Coulomb’s law, the electric field at P due to this length dx is

$dE'=\frac{1}{4\pi \epsilon}\frac{\lambda dx}{(PC)^2}$

But

⇒

This electric field at P can be resolved into two components as dEcosθ and dEsinθ. When the entire length AB is considered, then the dEsinθ components add up to zero due to symmetry. Hence, there is only dEcosθ component.

So, the net electric field at P due to dx is

dE' = dE cosθ

⇒ ………………….(1)

In ΔPOC,

⇒ x = h tan θ

Differentiating both sides w.r.t. θ,

⇒ dx = h sec ² θ dθ …………………….(2)

Also, h ² + x ² = h ² + h ² tan ² θ

⇒ h ² + x ² = h ² (1+ tan ² θ)

⇒ h ² + x ² = h ² sec ² θ ………….(3)

(Using the trigonometric identity, 1+ tan ² θ = sec ² θ)

Using equations (2) and (3) in equation (1),

The wire extends from to since it is very long.

Integrating both sides,

1515132016477995

This is the net electric field due to a long wire with linear charge density λ at a distance h from it.

In the question linear charge density =E

therefor

$E'=\frac{E}{2\pi \epsilon h}$

Q 1.31 It is now believed that protons and neutrons (which constitute nuclei of ordinary matter) are themselves built out of more elementary units called quarks. A proton and a neutron consist of three quarks each. Two types of quarks, the so called ‘up’ quark (denoted by u) of charge + $\left ( \frac{2}{3} \right )$ e, and the ‘down’ quark (denoted by d) of charge $\left (- \frac{1}{3} \right )$ e, together with electrons build up ordinary matter. (Quarks of other types have also been found which give rise to different unusual varieties of matter.) Suggest a possible quark composition of a proton and neutron.

Answer:

Given, a proton and a neutron consist of three quarks each.

And, ‘up’ quark is of charge + $\left ( \frac{2}{3} \right )$ e, and the ‘down’ quark of charge $\left (- \frac{1}{3} \right )$ e

Let the number of 'up' quarks be n. Therefore, the number of 'down' quarks is (3-n).

$\therefore$ The net charge = $\\ n\times\frac{2}{3}e + (3-n)\frac{-1}{3}e = (n-1)e$

Now, a proton has a charge +1e

$\therefore$ $(n-1)e = +1e \implies n =2$

Proton will have 2 u and 1 d, i.e, uud

Similarly, the neutron has a charge 0

$\therefore$ $(n-1)e = 0 \implies n =1$

Neutron will have 1 u and 2 d, i.e, udd

Q 1.32 (a) Consider an arbitrary electrostatic field configuration. A small test charge is placed at a null point (i.e., where E = 0) of the configuration. Show that the equilibrium of the test charge is necessarily unstable.

Answer:

For equilibrium to be stable, there must be a restoring force and hence all the field lines should be directed inwards towards the null point. This implies that there is a net inward flux of the electric field. But this violates Gauss's law, which states that the flux of electric field through a surface not enclosing any charge must be zero. Hence, the equilibrium of the test charge cannot be stable.

Therefore, the equilibrium is necessarily unstable.

Q 1.32 (b) Verify this result for the simple configuration of two charges of the same magnitude and sign placed a certain distance apart.

Answer:

Two charges of same magnitude and sign are placed at a certain distance apart. The mid-point of the line joining these charges will have E =0.

When a test charged is displaced along the line towards the charges, it experiences a restoring force(which is the condition for stable equilibrium). But if the test charge is displaced along the normal of the line, the net electrostatic force pushes it away from the starting point. Hence, the equilibrium is unstable.

Q 1.33 A particle of mass m and charge (–q) enters the region between the two charged plates initially moving along x-axis with speed vx .The length of plate is L and an uniform electric field E is maintained between the plates. Show that the vertical deflection of the particle at the far edge of the plate is $\frac{qEL^{2}}{2mv_{x}^{2}}$ .

Answer:

Let s be the vertical deflection, t be the time taken by the particle to travel between the plates

$\therefore$ $s = ut + \frac{1}{2}at^2$

Here , u =0 , since initially there was no vertical component of velocity.

The particle in the elecric field will experience a constant force (Since, Electric field is constant.)

F = ma = -qE (Using Newton's Second Law, F = ma)

$\therefore$ a = -qE/m (-ve sign implies here in downward direction)

Again, t = Distance covered/ Speed = $L/ v_{x}$

(In x-direction, since there is no force, hence component of velocity in x-direction remains constant = $v_{x}$ .

And, the distance covered in x-direction = length of the plate = L)

Putting these values in our deflection equation,

$\\ s = ut + \frac{1}{2}at^2 = (0)(L/v_{x}) + \frac{1}{2}(-qE/m)(L/v_{x})^2 \\ \implies s =\frac{-qEL^2}{2mv_{x}^2}$

(S is -ve, which implies it deflect in downwards direction.)

$\therefore$ The vertical deflection of the particle at the far edge of the plate is $\frac{qEL^{2}}{2mv_{x}^{2}}$ .

This motion is similar to the motion of a projectile in a gravitational field, which is also a constant force. The force acting on the particle in the gravitational field is mg whiles in this case, it is qE. The trajectory will be the same in both cases.

Q 1.34 Suppose that the particle in is an electron projected with velocity $v_{x}=2.0 \times 10^{6}ms^{-1}$ . If E between the plates separated by 0.5 cm is $9.1 \times 10^{2}\frac{N}{C}$ , where will the electron strike the upper plate? (|e|= $\left | e \right |=1.6 \times 10^{-19}, m_{e}=9.1\times 10^{-31}kg$ )

Answer:

$\therefore$ The vertical deflection of the particle at the far edge of the plate is $s=\frac{qEL^{2}}{2mv_{x}^{2}}$

given s= 0.5cm=0.005cm

calculate for L from the above equation

$L=\sqrt{\frac{2smv_x^2}{qE}}=\sqrt{\frac{2\times 0.005\times 9.1\times 10^{-31}(2\times10^6)^2 }{1.6\times 10^{-19}\times9.1\times10^2}}$

L=1.6 cm

class 12 physics chapter 1 ncert solutions is very important for board exams, JEE, and NEET. It covers basic concepts like electric charges, Coulomb's law, and electric fields. Understanding these basics is essential for success in board exams, where questions test these fundamentals. In competitive exams like JEE and NEET, a strong grasp of class 12 physics chapter 1 exercise solutions is crucial for the physics section. Moreover, this chapter's concepts are interconnected with later chapters in Class 12, forming the groundwork for more advanced physics topics. So, mastering electric charges and fields class 12 is not only exam-important but also essential for building a strong physics foundation.

NCERT Solutions for Class 12 Physics- Chapter Wise

Electric Charges and Fields

Electrostatic Potential and Capacitance

Current Electricity

Moving Charges and Magnetism

Magnetism and Matter

Electromagn etic Induction

Alternating Current

Electromagnetic Waves

Ray Optics and Optical Instruments

Wave Optics Solutions

Dual nature of radiation and matter

Atoms

Nuclei

Semiconductor Electronics Materials Devices and Simple Circuits

Electric charges and fields class 12 NCERT solutions: Important Formulas and Diagrams

In class12 physics ch1 ncert solutions, you'll find important formulas and diagrams that aid in understanding electrostatic concepts. These resources are valuable for exam preparation and building a strong foundation in electrostatics.

Coulomb's Law

$\\F\propto \frac{Q_{1}Q_{2}}{r^{2}}\\F=\frac{KQ_{1}Q_{2}}{r^{2}}$

Where:

K is the proportionality, Constant and Q1 and Q2 are two-point charges.

The vector form of Coulomb's Law:

1694162339206

1694162340518

Electric Field

Electric Field Intensity(E):

1694162341409

Where:

F is the force experienced by qo. The SI unit of E is V/m.

Electric Field Due To A Point Charge:

1694162370131

Electric Flux :

>> Flux is a scalar quantity. The SI unit of flux is volt-meter or newton-meter.

Electric Dipole:

1694162422500

Electric Dipole Moment:

Where: 2l is the dipole length.

>> The electric dipole moment is a vector quantity and the S.I unit is coulomb-meter (C-m).

Gauss's Law

The total electric flux through a closed surface enclosing a charge q is equal to times the total charge q enclosed by the surface.

Topics Covered in Class 12 NCERT Chapter Electric Charges and Fields:

The main topics covered in the ch 1 Physics class 12 are:

Charge and its properties

This NCERT Class 12 topic discuss the concept of charge with practical examples of charging through friction, conduction and induction. Also, the concepts of properties like conservation, additivity and quantisation of charge are discussed in the chapter electric charges and fields. Questions based on this are present in electric charges and fields Class 12 solutions.

Coulomb's law and its applications

Coulomb's law discusses the relation between the force exerted between two charges separated by a distance. For example, questions 1 and 12 of NCERT solutions for Class 12 chapter 1 uses this law to solve it.

Electric field: electric field and properties of electric field lines are discussed in this topic
Electric dipole: The concepts of dipole and field due to dipole at the axial, equatorial and general point and torque due to electric dipole are discussed.
Continuous charge distribution: Linear charge, surface charge and volume charge distributions are covered in this class 12 NCERT Physics chapter 1 topic
Electric flux, Gauss's law and its applications: The concepts of electric flux, the relation between electric charge and flux and application of Gauss law to different charge configurations are discussed in class 12 NCERT.

All the topics mentioned in Physics Class 12 chapter 1 are important and students are advised to go through all the concepts mentioned in the topics. Questions from all the above topics are covered in the electric charges and fields NCERT solutions.

Importance of NCERT Solutions for Class 12 Physics Chapter 1 Electric Charges and Fields in Board Exams:

The physics paper for the CBSE board exam is for 70 marks. In 2019 CBSE board exam 9 marks questions were asked from class 12 chapter 1 physics that includes the first two chapters, and this makes solving NCERT class 12 physics chapter 1 quite important. Practicing problems from the NCERT class 12 Physics solutions chapter 1 help students to score well in the final exam. Students can also use NCERT class 12 Physics chapter 1 solutions pdf download button to read chapter 1 physics class 12 NCERT solutions offline.

Key Features of Class 12 Electric Field and Charges NCERT Solutions

Comprehensive Coverage: This chapter covers fundamental concepts related to electric charges, Coulomb's law, electric fields, and their applications.
Exercise and Additional Exercise Questions: It includes a wide range of exercises and additional exercise questions to practice and assess understanding.
Detailed Solutions: Class12 physics ch1 ncert solutions provided in the NCERT textbook and supplementary materials offer step-by-step explanations for better comprehension.
Foundation for Advanced Topics: The concepts introduced in this class 12 physics chapter 1 ncert solutions serve as the building blocks for more complex topics in electromagnetism and modern physics.
Preparation for Exams: A strong grasp of this electric charges and fields class 12 is essential for success in board exams, JEE, and NEET.
Interconnected Concepts: ncert solution class 12 physics chapter 1 establishes connections to later chapters in the Class 12 physics syllabus like the gravitation chapter, emphasizing its significance.

Also Check NCERT Books and NCERT Syllabus here:

NCERT Exemplar Class 12 Solutions

NCERT Exemplar Class 12 Chemistry Solutions

NCERT Exemplar Class 12 Mathematics Solutions

NCERT Exemplar Class 12 Biology Solutions

NCERT Exemplar Class 12 Physics Solutions

Subject Wise Solutions

Excluded Content:

Certain portions of the chapter have been omitted or removed. These exclusions include:

Activity involving paper strips and the creation of an electroscope from Section 1.2 on Electric Charge.
The concept related to earthing in Section 1.3 on Conductors and Insulators.
The topic of Charging by Induction from Section 1.4.
Exercises numbered 1.13 and the range of exercises from 1.25 to 1.34.

These exclusions from class 12 electric charges and fields ncert solutions should be noted by students, and they should refer to their course materials for a precise understanding of what is covered in their syllabus.

Frequently Asked Question (FAQs)

1. What is the weightage of the chapter electric fields and charges for CBSE board exam

From the Class 12 Physics Chapter 1 NCERT solutions electric charges and fields 3 to 5 marks questions can be expected for CBSE bord exam. Questions based on the NCERT exercise questions can be expected for the exam. So practising the NCERT solutions for Class 12 Physics chapter 1 is important. The questions may be theory based, numerical or derivations.

2. Where can I find complete solutions of NCERT class 12 Physics

The detailed NCERT Class 12 Physics solutions chapter 1 is provided by careers 360. All the exercise and additional exercise questions of NCERT chapter Electric charges and Fields are solved with necessary explanations.

3. Whether the unit electrostatics is helpful in higher studies?

Yes, it is helpful in engineering streams and for research in the science field. The concepts studied in electrostatics will be useful in electrical and electronics-related branches.

4. What are the important topics of physics NCERT class 12 chapter 1

The two important laws discussed in NCERT solutions for Class 12 Physics Chapter 1 are important. That is the Coulombs law and the Gauss law. The derivations using Gauss laws and numerical related to both laws are important.

5. What is the weightage of electric charges and fields in JEE Mains

In JEE mains around 3.3% of questions are asked from the Physics class 12 chapter 1 questions and answers. That is 1 to 2 questions can be expected.

6. What is the weightge of NCERT chapter electric charges and fields for neet exam

For NEET exam 4% questions can be expected from the NCERT physics chapter 1 Electric Charges and Fields.

7. What are the main topics to be covered for NCERT Class 12 Physis Chapter 1 solutions

Electric Charge
Conductors And Insulators
Charging By Induction
Basic Properties Of Electric Charge
Coulomb’s Law
Electric Field
Electric Field Lines
Electric Flux
Electric Dipole
Continuous Charge Distribution
Gauss’s Law And Applications

8. Can I prepare for the CBSE Exam with the NCERT Solutions for Class 12 Physics Chapter 1?

The experts at Careers360 created the ncert solution for class 12 physics chapter 1 to assist students in acing the board test with confidence. To boost pupils' confidence, the key principles are presented in the most organised manner possible. NCERT Solutions address every little nuance to aid students in their board exam preparation.

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Questions related to CBSE Class 12th

Have a question related to CBSE Class 12th ?

I got 88.6% in cbse class 12th.Will I get admission in B.Sc at DU?

Hello student,

Hope you are in good health, so the answer to your question is as follows:-

First of all please get registered to delhi university admissions and fill the application fees.

Then try to calculate your best 4 according to the course .

As you have not mentioned which category you belong to , I am assuming you to be a general category student. So ,suppose if your best four came out to be somewhere like 89 , so if I see the last years cutoff for every BSC course the last cutoff comes out to be 89 , 87 where you can get bsc home science and bsc life science according to last year cutoff , but it always the chance of matter every year , cutoff always surprise us so you have to look every cutoff and when you find that you are getting the cutoff for that particular course do visit immediately to that college with all the correct papers and do the admission right away .

For further details you can go through the following link:-

https://university.careers360.com/articles/du-cutoff

Hope this helps!

Read Complete Answer

Manisha nayak 16 August,2021

i got 95.6%in cbse class 12th.. and best four % is 94%. i want take admission in du for bcom course. what are the chances for getting best colleges and expected college i can get?

Hello pallavi,
Your percentage is decent for good college in du university for your desired stream..

Check this college predictor to check in which colleges the chances of your admission are high

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Priyank Sharma 19 July,2020

I got 85% in CBSE CLASS 12TH EXAMINATION . Am I eligible to get admission in Du for BSc Hons ( computer science) ? if no then is there any other way to get admission in bsc Hons in du apart from merit based

Hello dear,
Your percentage is decent for good college in du university for your desired stream..

Check this college predictor to check in which colleges the chances of your admission are high

https://university.careers360.com/delhi-university-college-predictor

For more query please replay in the comments section..
Best of luck!!!

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Priyank Sharma 19 July,2020

i couldn't clear 1st compartment (which held in August 2022) cbse class 12th so can I give improvement in all subjects which to be held on March 2023. tell me a solution i need more than 75% in class 12th

hello,

Yes you can appear for the compartment paper again since CBSE gives three chances to a candidate to clear his/her exams so you still have two more attempts. However, you can appear for your improvement paper for all subjects but you cannot appear for the ones in which you have failed.

I hope this was helpful!

Good Luck

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Upasana Barman 24 August,2022

i was not able to clear 1st compartment and now I have to give 2nd compartment so can I give improvement exam next year? plz tell me very much tensed(cbse class 12th)

Hello dear,

If you was not able to clear 1st compartment and now you giving second compartment so YES, you can go for your improvement exam next year but if a student receives an improvement, they are given the opportunity to retake the boards as a private candidate the following year, but there are some requirements. First, the student must pass all of their subjects; if they received a compartment in any subject, they must then pass the compartment exam before being eligible for the improvement.

As you can registered yourself as private candidate for giving your improvement exam of 12 standard CBSE(Central Board of Secondary Education).For that you have to wait for a whole year which is bit difficult for you.

Positive side of waiting for whole year is you have a whole year to preparing yourself for your examination. You have no distraction or something which may causes your failure in the exams. In whole year you have to stay focused on your 12 standard examination for doing well in it. By this you get a highest marks as a comparison of others.

Believe in Yourself! You can make anything happen

All the very best.

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Mayankjha.student2007 23 August,2022

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Popular CBSE Class 12th Questions

A block of mass 0.50 kg is moving with a speed of 2.00 ms^-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1) $0.34\; J$	Option 2) $0.16\; J$
Option 3) $1.00\; J$	Option 4) $0.67\; J$

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up ? Fat supplies 3.8×10⁷J of energy per kg which is converted to mechanical energy with a 20% efficiency rate. Take g = 9.8 ms⁻² :

Option 1)

2.45×10⁻³ kg

Option 2)

6.45×10⁻³ kg

Option 3)

9.89×10⁻³ kg

Option 4)

12.89×10⁻³ kg

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1) $2,000 \; J - 5,000\; J$	Option 2) $200 \, \, J - 500 \, \, J$
Option 3) $2\times 10^{5}J-3\times 10^{5}J$	Option 4) $20,000 \, \, J - 50,000 \, \, J$

A particle is projected at 60⁰ to the horizontal with a kinetic energy $K$ . The kinetic energy at the highest point

Option 1) $K/2\,$	Option 2) $\; K\;$
Option 3) $zero\;$	Option 4) $K/4$

In the reaction,

$2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}$

Option 1) $11.2\, L\, H_{2(g)}$ at STP is produced for every mole $HCL_{(aq)}$ consumed	Option 2) $6L\, HCl_{(aq)}$ is consumed for ever $3L\, H_{2(g)}$ produced
Option 3) $33.6 L\, H_{2(g)}$ is produced regardless of temperature and pressure for every mole Al that reacts	Option 4) $67.2\, L\, H_{2(g)}$ at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, $Mg_{3}(PO_{4})_{2}$ will contain 0.25 mole of oxygen atoms?

Option 1) 0.02	Option 2) 3.125 × 10^-2
Option 3) 1.25 × 10^-2	Option 4) 2.5 × 10^-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1) decrease twice	Option 2) increase two fold
Option 3) remain unchanged	Option 4) be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1) Molality	Option 2) Weight fraction of solute
Option 3) Fraction of solute present in water	Option 4) Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol^-1) is

Option 1) twice that in 60 g carbon	Option 2) 6.023 × 10²²
Option 3) half that in 8 g He	Option 4) 558.5 × 6.023 × 10²³

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t²) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m² , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1) less than 3	Option 2) more than 3 but less than 6
Option 3) more than 6 but less than 9	Option 4) more than 9

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