Phys 3 Atomic and Quantum

A beam of monochromatic radiation is made up of photons each of momentum p. The intensity of the beam is doubled without changing frequency. What is the momentum of each photon after the change?

• p/2

• p

• 2p

• 4p

When green light is incident on a clean zinc plate no photoelectrons are emitted. What change may cause the emission of photoelectrons?

• Using a metal plate with larger work function

• Changing the angle of incidence of the green light on the zinc plate

• Using shorter wavelength radiation

• Increasing the intensity of the green light

A photoelectric cell is connected in series with a battery of emf 2 V. Photons of energy 6 eV are incident on the cathode of the photoelectric cell. The work function of the surface of the cathode is 3 eV. What is the maximum kinetic energy of the photoelectrons that reach the anode?

• 1 eV

• 3 eV

• 5 eV

• 8 eV

Which of the following is evidence for the wave nature of the electron?

• Continuous energy spectrum in β– decay

• Electron diffraction from crystals

• Existence of atomic energy levels

• Existence of nuclear energy levels

Monochromatic electromagnetic radiation is incident on a metal surface. The kinetic energy of the electrons released from the metal

• is constant because the photons have a constant energy.

• is constant because the metal has a constant work function

• varies because the electrons are not equally bound to the metal lattice.

• varies because the work function of the metal is different for different electrons.

Different metal surfaces are investigated in an experiment on the photoelectric effect. A graph of the variation of the maximum kinetic energy of photoelectrons with the frequency of the incident light is drawn for each metal. Which statement is correct?

• All graphs have the same intercept on the frequency axis.

• The work function is the same for all surfaces.

• All graphs have the same slope.

• The threshold frequency is the same for all surfaces.

Photoelectrons are emitted at a certain rate when monochromatic light is incident on a metal surface. Light of the same intensity but of higher frequency is now used. After this change, the rate of emission of electrons from the surface is

• zero.

• lower

• the same

• higher

A particle of light is called a...

• Photoelectron

• Photon

• Proton

• Electron

The diagram shows a circuit involving a photoelectric cell. When UV light is shone onto the metal cathode, electrons are emitted establishing a photocurrent.
Which of the following changes could cause the photocurrent to stop?

• Increasing the potential difference of the power supply.
• Increasing the frequency of the UV light.
• Increasing the intensity of the UV light.
• Changing the metal surface to one with a smaller work function.

The graph shows maximum kinetic energy of emitted electrons against frequency of incident light for a number of different metals.
Plank's constant is determined by:

• the x-intercept.
• the y-intercept.
• the gradient.
• the area under the graph.