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We come across amazing examples of the dual nature of matter and radiation in our daily lives. The operation of solar panels, for example, depends on the photoelectric effect, in which light releases electrons from a metal surface by acting as distinct energy packets known as photons. Similarly, electron microscopes go beyond the capabilities of optical microscopes by using the wave-like characteristics of electrons to produce high-resolution imaging.
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This interesting concept is explored in depth in NCERT Exemplar Class 12 Physics Solutions of Chapter 11, which examines the dual properties of electromagnetic waves. It describes in detail how light has both particle-like and wave-like characteristics, which are confirmed by a number of studies. The chapter gives a thorough description of electromagnetic waves' characteristics and characterizes them as energy bundles, or quanta, called photons.
Also see - NCERT Solutions for Class 12 Physics
Question:1
Answer:
The answer is the option (d)Question:2
The wavelength of a photon needed to remove a proton from a nucleus which is bound to the nucleus with 1 MeV energy is nearly
(a) 1.2 nm
(b) 1.2 x 10-3 nm
(c) 1.2 x 10-6 nm
(d). 1.2 x 10 nm
Answer:
The answer is the option (b)Question:3
Consider a beam of electrons (each electron with energy E0) incident on a metal surface kept in an evacuated chamber. Then
(a) no electrons will be emitted as only photons can emit electrons
(b) electrons can be emitted but all with an energy, E0
(c) electrons can be emitted with any energy, with a maximum of E0 –
(d) electrons can be emitted with any energy, with a maximum of E0
Answer:
The answer is the option (d) When a beam of electrons (each electron with energy E0 ) incident on a metal surface is kept in an evacuated chamber, energy of incident electrons will be transferred to the emitted electrons due to elastic collisions. A part of E0 of incident electrons is consumed against work function to emit the electrons. Thus, the maximum energy of emitted electrons is E0Question:4
Consider Fig. 11.7 in the NCERT textbook of physics for Class XII. Suppose the voltage applied to A is increased. The diffracted beam will have the maximum at a value of θ that
(a) will be larger than the earlier value
(b) will be the same as the earlier value
(c) will be less than the earlier value
(d) will depend on the target
Answer:
The answer is the option (c)Question:5
Answer:
The answer is the option (b)Question:6
An electron is moving with an initial velocity v = v0i and is in a magnetic field B = B0j. Then, its de-Broglie wavelength
(a) remains constant
(b) increases with time
(c) decreases with time
(d) increases and decreases periodically
Answer:
The answer is the option (a)Question:7
Answer:
The answer is the option (a)Question:8
Answer:
The correct answer is option (c)Question:9
Answer:
The answer is the option (c, d)Question:10
Two particles A1 and A2 of masses m1, m2 (m1 > m2) have the same de Broglie wavelength. Then
(a) their momenta are the same
(b) their energies are the same
(c) energy of A1 is less than the energy of A2
(d) energy of A1 is more than the energy of A2
Answer:
The answer is the option (a. c)Question:11
The de Broglie wavelength of a photon is twice the de Broglie wavelength of an electron. The speed of the electron is ve = c/100. Then
(a) Ee/Ep = 10-4
(b) Ee/Ep = 10-2
(c) Pe/mec = 10-2
(d) Pe/mec = 10-4
Answer:
The answer is the option (b,c)At ordinary temperature, the energy of thermal neutrons
de Broglie wavelength of the electron
de Broglie wavelength of the proton is
Question:12
Photons absorbed in the matter are converted to heat. A source emitting n photon/sec of frequency ν is used to convert 1kg of ice at 0°C to water at 0°C. Then, the time T taken for the conversion
(a) decreases with increasing n, with ν fixed
(b) decreases with n fixed, ν increasing
(c) remains constant with n and ν changing such that nν = constant
(d) increases when the product nν increases
Answer:
The answer is the option (a, b. c).Question:13
A particle moves in a closed orbit around the origin, due to a force which is directed towards the origin. The de-BrOglie wavelength of the particle varies cyclically between two values
(a) The particle could be moving in a circular orbit with origin as centre
(b) The particle could be moving in an elliptic orbit with origin as its focus
(c) When the de-Broglie wavetength is
(d) When the de-Broglie wavelength is
Answer:
The answer is the option (b,d)Question:14
Answer:
It is given that the proton andQuestion:15
(i) In the explanation of photoeletric effect, we assume one photon of frequency v collides with an electron and transfers its energy. This leads . to the equation for the maximum energy Emax of the emitted electron as
where
(ii) Why is this fact (two photon absorption) not taken into consideration in our discussion of the stopping potential?
Answer:
(i) In the question, 2 photons transfer its energy to one electron as E=hvQuestion:16
Answer:
With an increase in the wavelength of the photon, there is a decrease in the frequency or increase in the energy of the photon. Let us consider 2 possible cases:Question:17
Do all the electrons that absorb a photon comes out as photo electrons?
Answer:
A common observation in the photoelectric effect is that most of the electrons knocked by photons are scattered into the metal by absorbing photons. In order to escape from the surface, the electron must absorb enough energy to overcome the positive ion attraction in the material of the surface.Question:18
Answer:
Let EX and EV be the energies given by one photon in X-rays andQuestion:19
Answer:
There is a transfer of momentum to the atoms on the metal surface when the photons strike the surface. This also results in a decrease in speed of the photons. Thus, the momentum of photons is transferred to the nucleus and electrons of the metal.Question:20
Answer:
Let the maximum energies of emitted electrons be K1 and K2 when 600 nm and 400 nm visible light are used according to questionQuestion:21
Answer:
As the electrons rotate in a circular path,Question:22
Answer:
Question:23
Answer:
The de-Broglie wavelength is given byQuestion:24
Answer:
According to the Bragg’s law of diffraction, condition for the nth maxima is given byQuestion:25
Answer:
Area (A)=10-2 cm2=10-4m2Question:26
Answer:
Question:27
(i) Which material A or B has a higher work function?
(ii)Given the electric charge of an electron = 1.6 x 10-19C, find the value of h obtained from the experiment for both A and B. Comment on whether it is consistent with Einstein's theory.
Answer:
We know thatQuestion:28
Answer:
When the collision is elastic, law of conservation of momentum is followed.Question:29
Consider a 20 W bulb emitting light of wavelength 5000
(i) Estimate no. of photons emitted by the bulb per second. [Assume no other losses]
(ii) Will there be photoelectric emission?
(iii) How much time would be required by the atomic disk to receive energy equal to work function (2 eV)?
(iv) How many photons would atomic disk receive within time duration calculated in (iii) above?
(v) Can you explain how photoelectric effect was observed instantaneously?
Answer:
Given that
i) Number of photon emitted by bulb per second=
ii Energy of the incident photon=
iii Time required by the atomic disk to receive energy is=28.4 sec
Let the time spent be
Energy transferred by the bulb in full solid angle to atoms=
(iv) Number of photons received by the atomic disk
(iv) We say that photoelectric emission is instantaneous as it involves a collision between the incident photon and free electron lasting for a very short span of time, say
In order to understand how electromagnetic waves' special characteristics allow for a range of physical occurrences, students will look into a number of questions related to their nature. A number of important experiments that support the dual nature of electromagnetic waves are also included in the NCERT Exemplar answers for Class 12 Physics, Chapter 11. Students have a better understanding of how these concepts are developed and how they helped in subsequent scientific breakthroughs thanks to these activities. Furthermore, this chapter presents the historical development of these discoveries in an organized fashion, highlighting the contributions made by numerous scientists throughout a range of time periods in discovering the true nature of electromagnetic waves.
where:
-
-
-
-
Threshold Frequency (
- The minimum frequency of light required to eject electrons from a metal surface.
- If
Stopping Potential
where
de-Broglie Wavelength:
where:
-
-
Chapter 11 Dual Nature of Radiation and Matter |
As per latest 2024 syllabus. Maths formulas, equations, & theorems of class 11 & 12th chapters
These questions are solved keeping in mind the CBSE pattern and how the marks are divided as per the steps.
Yes, one can download these questions so that one uses the solutions offline.
Try to understand the NCERT exemplar solutions for Class 12 Physics chapter 11 and connect them to the topics that one has studied in the chapter.
One will learn in detail about wave theory of light, particle nature of light, photoelectric effect, Davisson and Germer experiment, etc.
Changing from the CBSE board to the Odisha CHSE in Class 12 is generally difficult and often not ideal due to differences in syllabi and examination structures. Most boards, including Odisha CHSE , do not recommend switching in the final year of schooling. It is crucial to consult both CBSE and Odisha CHSE authorities for specific policies, but making such a change earlier is advisable to prevent academic complications.
Hello there! Thanks for reaching out to us at Careers360.
Ah, you're looking for CBSE quarterly question papers for mathematics, right? Those can be super helpful for exam prep.
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Have you checked out the CBSE sample papers on their official website? Those are usually pretty close to the actual exam format. You could also look into previous years' board exam papers - they're great for getting a feel for the types of questions that might come up.
If you're after more practice material, some textbook publishers release their own mock papers which can be useful too.
Let me know if you need any other tips for your math prep. Good luck with your studies!
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As per latest 2024 syllabus. Physics formulas, equations, & laws of class 11 & 12th chapters
As per latest 2024 syllabus. Chemistry formulas, equations, & laws of class 11 & 12th chapters