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Dual Nature of Radiation and Matter 3 Mark Creative Question Paper With Answer Key

12th Standard

    Reg.No. :
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Physics

Time : 00:45:00 Hrs
Total Marks : 42

    3 Marks

    14 x 3 = 42
  1. Derive an expression for De Broglie wave length.

  2. (a) Define the term 'intensity of radiation' in terms of photon picture of light.
    (b) Two monochromatic beams, one red and the other blue; have the same intensity. In which case
    (i) the number of photons per unit area per second is larger,
    (ii) the maximum kinetic energy of the photoelectrons is more? Justify you answer.

  3. List out the laws of photoelectric effect. (or) Write any three Laws of Photoelectric Effect

  4. A proton and an electron have same velocity. Which one has greater de Broglie wavelength and why?

  5. When the electron orbiting in a hydrogen atom in its ground state moves to the third excited state, show how the de Broglie wavelength associated with it would be affected?

  6. The graph shows the variation of stopping potential with frequency of incident radiation for two photosensitive metals A and B. Which one of the two has higher value of workfunction? Justify your answer.

  7. An electron and a proton have the same kinetic energy. Which one of the two has the larger de Broglie wavelength and why?

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

  9. (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?

  10. The frequency V of incident radiation is greater than threshold frequency (vo) in a photocell. How will the stopping potential vary if frequency (v) is increased, keeping other factors constant?

  11. Two metals A and B have work functions 4eV and 10eV respectively. Which metal has the higher threshold wavelength?

  12. de Broglie wavelength associated with an electron accelerated through a potential difference V is \(\lambda\). What will be the de Broglie wavelength when the accelerating potential is increased to 4 V?

  13. Red light however bright it is, cannot produce the emission of electrons from a clean zinc surface, but even weak ultraviolet radiation can do so; why?

  14. Give the applications photocell.

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