IIT JEE MCQ Quiz Hub

1. Three particles having their charges in the ratio of 1 : 3 : 5 produce the same spot on the screen in Thomson experiment. Their masses are in the ratio of
5:03:01
3:01:05
1:03:05
5 : 1 : 3

2. At stopping potential
K.E. = 0
P.E. = 0
K.E. = P.E
K.E. + P.E. = 0

3. If the momentum of a particle is doubled, then wavelength associated with particle will be
remains unchanged
half
double
None of these

4. If frequency of the wave emitted from a radio stations is 6 MHz. Then wavelength of waves will be
12 m
24 m
50 m
6 m

5. Photons of energy 5.0 eV fall on a metal surface whose work function is 2.0 eV. Then
most energetic electron will have kinetic energy equal to 5.0 eV
all photoelectrons will have same energy of 2.0 eV
kinetic energy of most energetic electron will be 2.0 eV
kinetic energy of most energetic electron will be 3.0 eV

6. A photo cell with a constant potential difference of V volts applied across its ends is illuminated by a point source from a distance of 25 cm. If the source is moved to a distance of 1 m, then electrons emitted from the photo cell will be
carry 1 / 4 th of their previous energy
are 1 / 6 th as numerous as before
are - 1 / 16 th as numerous as before
carry 1 / 4 th of their previous momentum

7. Rest mass energy of an electron is 0.54 MeV. If velocity of the electron is 0.8 C then K.E. of the electron is
0.36 MeV
0.41 MeV
0.48 MeV
1.32 MeV

8. A proton is accelerated through one volt. The increase in it K.E. is approximately
1870 eV
1 eV
300 eV
None of these

9. In Einstein s photoelectric equation E = hv - W where E stands for
K.E. of emitted electrons
Maximum P.E. of emitted electrons
Mean kinetic energy of the incident particles
Total energy of all the emitted electrons

10. If wavelength of an electron and a photon is same, then they will have same
Velocity
Momentum
Energy
All of above

11. It kinetic energy of the emitted electted electrons is zero for the incident light of wavelength 686 nm. Then wavelength of radiations emitting electrons having energy 1.81 eV will be (Given : work function of cesium = 1.81 eV)
686 nm
1372 nm
343 nm
2058 nm

12. Charge on a stationary oil drop in Millikan s experiment is ne. Potential difference between the plates is 400 volts. If mass of the drop is doubled without changing the charge, then potential drop required to keep the drop stationary is
200 volts
800 volts
1600 volts
3200 volts

13. Photon A has twice the wavelength of photon B then energy of photon A is
Half that of B
Twice that of B
Thrice that of B
Four times that of B

14. Work function of aluminium is 4.2 eV. If two photons each of energy 3.5 eV strike an electron of aluminum, then emission of electron
will be possible
depends on the smoothness of the surface
will not be possible
None of these

15. When a monochromatic point source of light is at a distance of 0.2 m from photoelectric cell, the cut-off voltage and the saturation current are 0.6 V and 18.0 mA respectively. If the same source is placed 0.6 m away from the photo cell, then
the stopping potential will be 0.2 V
the stopping potential will be 0.6 V
the saturation current will be 2.0 mA
the saturation current will be 6.0 mA

16. Rest mass of an electron is 051 MeV If it is given a velocity of 08 c its kinetic energy will be
0.27 MeV
0.34 MeV
0.68 MeV
0.68 MeV

17. Rest mass of a photo is
9.31 eV
13.6 eV
2.6 eV
zero

18. If photons of 60 nm are incident on hydrogen then max KE of the emitted electrons will be
5.0 eV
6.3 eV 6.3 eV
7.0 eV
7.9 eV

19. When distance between a monochromatic source and photo cell is 20 cm then cut off voltage and saturation currents are 0.6 volt and 18.0 mA respectively . If distance between the two is increased to 60 cm then
saturation current will be 2.0 mA
saturation current will be 6.0 mA
stopping potential will be 0.2 volt
stopping potential will be 0.6 volt

20. When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell cut off voltage and the saturation current are respectively 0.6 V and 18.0 mA. If same source is placed 0.6 m away from the photoelectron cell then
saturation current will be 1 / 4 th of their previous value
saturation current will be 18 mA
stopping potential will be 0.6 V
saturation current will be 6 mA