NCERT Class 12 Physics Chapter 2 Notes Electrostatic Potential and Capacitance

NCERT Class 12 Physics Chapter 2 Notes Electrostatic Potential and Capacitance - Download PDF

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NCERT Notes for CBSE Class 12 Physics Chapter 2 Electrostatic Potential and Capacitance - Download Free PDF

A solid understanding of fundamental concepts is essential for effective preparation in board exams, state exams, and competitive exams such as JEE and NEET. Comprehensive Electrostatic Potential and Capacitance class 12 notes are essential for efficiently revising chapters.

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These meticulously crafted physics class 12 chapter 2 notes pdf not only cover the fundamental concepts but also present critical formulas and practical insights in a clear manner. For a confident and successful exam journey, boost your preparation with Careers360's Electrostatic Potential and Capacitance notes class 12.

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NCERT Notes for CBSE Class 12 Physics Chapter 2 Electrostatic Potential and Capacitance - Download Free PDF
NCERT Class 12 Physics Chapter 2 Notes
Electric Potential:
Electric Potential Energy:
Relation Between Electric Field and Electric Potential:
Electric Potential Due to a Dipole:
Dielectrics and Polarization
Capacitor
Parallel Plate Capacitor:
Energy Stored in a Capacitor:
A Van de Graaff Generator:
Key Features of NCERT CBSE Class 12 Physics ch 2 Notes
NCERT Class 12 Notes Chapterwise
NCERT Books and Syllabus

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NCERT Class 12 Physics Chapter 2 Notes

Electric Potential:

The electrostatic potential in a region of the electric field is equal to the amount of work done in bringing a unit-positive test charge from infinity to that point against the electrostatic force.

$V=\frac{w}{q_0}$

Where,

w - work done and q0 - unit charge

Electric potential is a scalar quantity and the SI unit is Volt (V).
CGS unit is stat volt.
Dimension - $mL^{2}T^{-3}A^{-1}$ .

$1volt=\frac{1}{300}$ stat volt.

Potential due to system of point charges:

$V=\sum_{i=1}^{n}\frac{KQ_i}{r_i}$

Potential difference:

The potential difference between two points A and B in an electric field is equal to the amount of work done (by an external agent) in moving a unit positive charge from point A to another point B.

$V_B-V_A=\frac{w}{q}$

Where,

W is the amount of work done and q is the unit positive charge.

Electric potential due to a point charge:

$\\V=K\frac{q}{r}\\K=\frac{1}{4\pi\epsilon_0}$

Electric Potential Energy:

Consider a system with two charges, q₁ and q₂ fixed at points A and B, respectively, and separated by AB =r₂. If q₂ is moved from B to a new point C along AB and AC =r₂, and the charge is displaced from r to r + dr, then the work done (dW) is as follows:

dw=F.dr

$\\=\frac{Kq_1q_2}{r^2}.dr$

Total work done

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$\\W=\int_{r_1}^{r_2}\frac{Kq_1q_2}{r^2}.dr\\=\frac{q_1q_2}{4\pi\ \epsilon_0}[\frac{1}{r_1}-\frac{1}{r_2}]$

Change in potential energy

U(r_2)-U(r_1)=-W

$\\=\frac{q_1q_2}{4\pi\ \epsilon_0}[\frac{1}{r_2}-\frac{1}{r_1}]$

When the system of two charges have infinite separation then potential energy

$U(\infty)=0$

The potential energy when separation is r is

$\\U(r)=U(r)-U(\infty)\\=\frac{q_1q_2}{4 \pi \epsilon_0r}$

Relation Between Electric Field and Electric Potential:

If we know the electric potential in a region we can find the electric field

$dV=-Edr cos\theta$

where,

θ is the angle between E and dr

Electric Potential Due to a Dipole:

i) at axial point

$V_{axial}=\frac{kP}{\left ( r^{2}-l^{2} \right )}$

if r>>l

$V_{axi}=\frac{1}{4\pi \epsilon _{0}}\frac{P}{r^{2}}$

ii) at equatorial point:

$V_{equi}= 0$

iii) General point

$V_{g}=\frac{1}{4\pi \epsilon _{0}}\frac{P\cos \Theta }{r^{2}}$

Work done in rotation of dipole and equilibrium of dipole:

$W=PE\left ( \cos \Theta _{1} -\cos \Theta _{2}\right )$

$\\if \ \theta_1=90 \ and \ \theta_2=\theta\\W=-PEcos\theta=-P.E$

This work done is stored as potential energy.

Condition for the stable equilibrium of a dipole:

Angle (θ): The system is stable when the angle between the dipole moment (p) and the electric field (E) is 0° (aligned).
Torque: In this position, the net torque acting on the dipole is zero. Any slight deviation from this position causes a restoring torque, bringing the dipole back into alignment with the field.
Potential Energy: When the dipole is aligned with the electric field, its potential energy is at its lowest.

Condition for the unstable equilibrium of a dipole:

Angle (θ): The system is in unstable equilibrium when the angle between p and E is 180° (anti-aligned).
Torque: In this position, the net torque acting on the dipole is zero. Any small displacement from this position, however, produces a torque that increases the angle between p and E, pushing the dipole out of alignment.
Potential Energy: The dipole's potential energy is greatest when it is anti-aligned with the electric field.

Electrostatics of Conductors

At electrostatic equilibrium, the electric field inside a charged conductor is zero.
The electric field at every point on the surface of a charged conductor is normal (perpendicular) to the surface.
In a static situation, the excess charge on a charged conductor exists only on its surface.
There is no electric field inside the cavity of a conductor, providing electrostatic shielding.
At electrostatic equilibrium, the electrostatic potential remains constant throughout the conductor.

Dielectrics and Polarization

Dielectrics are non-conducting materials, and they do not have free charge carriers that can move easily within the material.

Non-Polar Molecules:

The centres of negative and positive charges coincide in a non-polar molecule. The non-polar molecule lacks a permanent dipole moment.

Example: O₂, H₂

Polar Molecule:

Polar molecules have negative and positive charge centres that are separated and have a permanent dipole moment.

Example: H₂O, HCl

NOTE :

Both polar and non-polar dielectrics acquire a net dipole moment in the presence of an external electric field.

Polarization:

It is the dipole moment per unit volume

$\small \\P=\chi_eE\\ \chi_e \text{ is the electric susceptibility of the dielectric medium}$

Polarized dielectrics are similar to two charge surfaces with an induced charge density of opposite polarity.

Capacitor

A capacitor is a system of two conductors, which are separated by an insulator. A capacitor is used to store a large amount of charge.

The charge stored in a capacitor:

$\small Q=CV$

where, C is capacitance and V is voltage

Capacitance (C):

The capacitance of a capacitor

$\small C=Q/V$

Dielectric Strength:

Dielectric strength is the maximum amount of electric field that a dielectric medium can withstand.

Parallel Plate Capacitor:

Two conducting plates of area A separated by a distance d. If the dielectric medium between the capacitor plate is vacuum or air, then

$\small C=\frac{\epsilon_0 A}{d}$

When a dielectric of dielectric constant k is inserted between the above capacitor, the new capacitance

$\small \\C'=\frac{k\epsilon_0 A}{d}\\C'=kC$

Combination of capacitors:

For n capacitors connected in parallel, the net value of capacitance is

$\small C=C_1+C_2+C_3+.........C_n$

For n capacitors connected in series, the net value of capacitance is

$\small \frac{1}{C}=\frac{1}{C_1}+\frac{1}{C_2}+\frac{1}{C_3}+..............\frac{1}{C_n}$

Energy Stored in a Capacitor:

The energy U stored in a capacitor of capacitance C, charge Q and voltage V is

$\small U=\frac{1}{2}CV^2$

The electric energy density

In a region with an electric field, the electric energy density,

$\small \text{Energy per unit volume}=\frac{1}{2}\epsilon_0E^2$

A Van de Graaff Generator:

Van de Graaff generator is used for accelerating charged particles. It consists of a large spherical conducting shell. The charge is continuously transferred to the shell with the help of a moving belt and brushes. The potential of million volts rebuilt up and can be used for accelerating the charged particles.

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Significance of NCERT Class 12 Physics Chapter 2 Notes

Electrostatic potential and capacitance Class 12 notes will be helpful to revise the chapter and to get an idea about the main topics covered in the chapter. Also, this NCERT class 12 physics chapter 2 notes are useful to cover the main topics of the class 12 CBSE physics syllabus and also for competitive exams like VITEEE, BITSAT, JEE Main, NEET etc. Class 12 physics chapter 2 notes pdf download can be used to prepare in offline mode.

Key Features of NCERT CBSE Class 12 Physics ch 2 Notes

Comprehensive coverage of key topics from Chapter 2 - Electrostatic Potential and Capacitance.
Electrostatic Potential and Capacitance class 12 notes are written in clear and concise language, making complex concepts simple to grasp.
Physics class 12 chapter 2 notes pdf concentrate on developing a solid conceptual foundation in electrostatic potential and capacitance.
Class 12 Physics chapter 2 notes are easily downloadable in PDF format, allowing for offline learning.
CBSE class 12 physics ch 2 notes designed to help with exam preparation for board and competitive exams such as JEE and NEET.

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