Quantum Mechanics MCQ

If the frequency of the incident radiation is equal to the threshold frequency, what will be the value of the stopping potential?

• 0

• Infinite

• 180 V

• 1220 V

If the intensity of incident radiation in a photo-cell is increased, how does the stopping potential vary?

• Increases

• Remains the same

• Decreases

• Infinite

Two beams, one of red light and the other of blue light, of the same intensity are incident on a metallic surface to emit photoelectrons. Which emits electrons of greater frequency?

• Both

• Red light

• Blue light

• Neither

How does retarding potential vary with the frequency of light causing photoelectric effect?

• Infinite

• Zero

• Decreases

• Increases.

If the intensity of the radiation incident on a photo-sensitive plate is doubled, how does the stopping potential change?

• Increases

• Decreases

• No effect

• Infinite

The stopping potential in photoelectric emission does not depend upon the frequency of the incident radiation.

• True

• False

The maximum kinetic energy of a photoelectron is 3 eV. What is the stopping potential?

• 0 V

• 3 V

• 9 V

• 12 V

In a waveguide, which of the following condition is true always?

• phase velocity = c

• group velocity = c

• phase velocity > c

• phase velocity < c

The product of the phase and the group velocities is given by the

• Speed of light

• Speed of light/2

• 2 x Speed of light

• (speed of light)/4

The phase velocity refers to a group of waves and the group velocity refers to a single wave. State true/false.

• True

• False