Page 1 CBSE TEST PAPER-03 CLASS - XII PHYSICS (Dual Nature of Matter and Radiation) 1. How does the stopping potential applied to a photocell change if the distance between the light source and the cathode of the cell is doubled? [1] 2. On what factor does the retarding potential of a photocell depend? [1] 3. Electron and proton are moving with same speed, which will have more wavelength? [1] 4. By how much would the stopping potential for a given photosensitive surface go up if the frequency of the incident radiations were to be increased from 4× 10 15 Hz to 8 × 10 15 Hz? ( ) 3 19 8 6.4 10 4 , 1.6 10 , 3 10 / h Js e C c m s - - = × = × = × [2] 5. Work function of Na is 2.3eV. Does sodium shoe photoelectric emission for light on the velocity of photoelectrons? [2] 6. An electron and an alpha particle have the same debroglie wavelength associated with them? How are their kinetic energies related to each other? [2] 7. An particle a - and a proton are accelerated from rest through same potential difference V. find the ratio of de–broglie wavelength associated with them? [2] 8. Photoelectric work function of a metal is 1eV. Light of wavelength 3000A o falls on it. What is the velocity of the effected photoelectron? [3] 9. The wavelength ? of a photon and debroglie wavelength of an electron have the same value. Show that the energy of the photon is 2 mc h ? times the kinetic energy of electron where m, c, and h have their usual meanings? [3] 10. Draw a graph showing the variation of stopping potential with frequency of the incident radiations. What does the slope of the line with the frequency axis indicate. Hence define threshold frequency? [3]Read More