CBSE Physics Electrons and Photons Test 2 Online

1. In a photosensitive cell, with exciting wavelength λ the fastest electron has speed v. If the existing wavelength is changed to 3λ/4, the speed of the fastest emitted electron will be ?

2. when ultraviolet rays are incident on metal plate, the photoelectric effect does not occur. It occurs by incidence of ?

3. In X-rays diffraction experiment distance between atomic lattice planes of diffraction grating is 2.8 x 10-10m then the maximum wavelength of X-rays (in metre) is ?

4. In a mas spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R  using a magnetic field B. If V and B are kept constant, the ratio [charge on the ion/mass of the ion] will be proportional too ?

5. The following particles are moving with the same velocity, then maximum de-Broglie wavelength will be for ?

6. The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the ?

7. An electron moves with a velocity 1 x 10³ m/s in a magnetic field of induction 0.3 T at an angle 30°. If e/m of electron is 1.76 x 10¹¹ C/Kg, the radius of teh path is nearly ?

8. A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted 2 m, then ?

9. Which of the following is not the property of cathode rays ?

10. Einstein's work on photoelectric effect gives support to ?

11. A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 x 10⁶ mas-1. The velocity of the particle is (mass of electron = 9.1 x 10^-31 kg) ?

12. J J Thomson's cathode ray tube experiment demonstrated that ?

13. In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of ?

14. A photocell employs photoelectric effect to convert ?

15. A 5 W source emits monochromatic light of wavelength 5000 A. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m, the number of photoelectrons liberated will be reduced by a factor of ?