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Dual Nature of Radiation and Matter

12th Physics - Dual Nature of Radiation and Matter Practice Question Paper

Dual Nature of Radiation and Matter Practice Question Paper

12th Standard

    Reg.No. :
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Physics

Time : 01:00:00 Hrs
Total Marks : 50
    5 x 1 = 5

  1. The wavelength λe of an electron and λp of a photon of same energy E are related by _____.

    (a)

    λp ∝ λe

    (b)

    \({ \lambda }_{ p }∝ \sqrt { { \lambda }_{ e } } \)

    (c)

    \({ \lambda }_{ p }∝ \frac { 1 }{ \sqrt { { \lambda }_{ e } } } \)

    (d)

    \({ \lambda }_{ p }∝ { \lambda }_{ e }^{ 2 }\)

  2. In an electron microscope, the electrons are accelerated by a voltage of 14 kV. If the voltage is changed to 224 kV, then the de Broglie wavelength associated with the electrons would _____.

    (a)

    increase by 2 times

    (b)

    decrease by 2 times

    (c)

    decrease by 4 times

    (d)

    increase by 4 times

  3. P and E denote the linear momentum and energy of a photon. If the wavelength is decreased ____________.

    (a)

    Both P and E increase

    (b)

    P increases and E decreases

    (c)

    P decreases and E increases

    (d)

    both P & E decrease

  4. The work function of a metal is hv0. Light of frequency v falls on this metal. The photoelectric effect will take place only if ___________.

    (a)

    v \(\geq\) v0

    (b)

    v > 2vo

    (c)

    vo

    (d)

    v > vo/2

  5. The minimum amount of energy required to liberate a photo electron from the metal surface is called as ________

    (a)

    cut-off energy

    (b)

    work function

    (c)

    threshold potential

    (d)

    potential energy

    6. 1 x 2 = 2

  6. Assertion: Electromagnetic radiations are regarded as waves.
    Reason: Because they exhibit interference, diffraction and polarization under some suitable circumstances.
    Codes:
    (a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
    (b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
    (c) Assertion is true but Reason is false.
    (d) Assertion is false but Reason is true.

    7. 1 x 2 = 2
  7. (a) Bremsstrahlung radiation - Breaking radiation
    (b) Neutron diffraction - Crystal structure
    (c) Nature of light - Polarization
    (d) Photo sensitive material - Carbon
    8. 2 x 1 = 2

  8. Correct Statement:
    (I) Cadmium show photoelectric emission for ultraviolet light.
    (II) Photosensitive materials eject photo electrons
    (III) The photo current becomes zero at a particular negative potential
    (IV) The liberation of electrons from any surface of a substance is electron emission.
    (a) I, II, III and IV
    (b) I and II only
    (c) I and III only
    (d) I, II and III only

  9. Correct Statement:
    (I) Metal selected for electron emission should have low work function.
    (II) Potential barrier presents leaving free electron from the metallic surface
    (III) Potential barrier created by the positive nuclei of the metal
    (IV) Electron in the outermost shells are tightly pound to the nucleus.
    (a) I and II only
    (b) II and III only
    (c) I, II and III only
    (d) I, II, III and IV

    10. 5 x 2 = 10

  10. Why do metals have a large number of free electrons?

  11. Define work function of a metal. Give its unit.

  12. What is photoelectric effect?

  13. What is surface barrier?

  14. Give example for photosensitive materials Why is called so?

    15. 3 x 3 = 9

  15. What do you mean by electron emission? Explain briefly various methods of electron emission.

  16. Show the variation of photocurrent with collector plate potential for different frequencies but same intensity of incident radiation.

  17. (i) Draw a graph showing variation of photoelectric current (I) with anode potential (V) for different intensities of incident radiation. Name the characteristic of the incident radiation that is kept constant in this experiment.
    (ii) If the potential difference used to accelerate electrons is doubled, by what factor does the de-Broglie wavelength associated with the electrons change?

    18. 4 x 5 = 20

  18. How many photons per second emanate from a 50 mW laser of 640 nm?

  19. Calculate the maximum kinetic energy and maximum velocity of the photoelectrons emitted when the stopping potential is 81 V for the photoelectric emission experiment.

  20. Give the applications photocell.

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