12.1 Interaction of Matter with Radiation

Which phenomenon best demonstrates the particle nature of light?

A. Diffraction

B. Interference

C. Photoelectric effect

D. Polarisation

What is the work function of a metal?

A. The maximum kinetic energy of emitted electrons.

B. The energy required to remove an electron from the metal.

C. The energy of the incident photon.

D. The energy difference between the conduction and valence bands.

In the Compton scattering experiment, if the incident photon has a longer wavelength than the scattered photon, what can be inferred?

A. The photon has lost energy.

B. The photon has gained energy.

C. The photon's energy remains unchanged.

D. The photon has been annihilated.

Which of the following best describes the Compton wavelength shift?

A. The change in wavelength of a photon after interaction with an electron.

B. The difference in wavelengths of incident and reflected photons.

C. The wavelength at which maximum scattering occurs.

D. The wavelength at which photon-electron interaction is minimal.

For pair production to occur, the energy of the incident photon must be:

A. Equal to the rest energy of an electron.

B. Less than the rest energy of an electron.

C. Greater than twice the rest energy of an electron.

D. Equal to the kinetic energy of an electron.

a) Describe the basic principles of the photoelectric effect and explain the significance of the threshold frequency. [3]

b) Light of frequency 8 x 10^14 Hz is incident on a metal surface with a work function of 3.5 x 10^-19 J. Determine if photoemission will occur. [2]

a) Define Compton scattering and explain its significance in understanding the particle nature of light. [3]

b) During a Compton scattering experiment, an X-ray photon of wavelength 0.05 nm is scattered by an electron. Calculate the change in wavelength if the scattering angle is 90 degrees. Use the Compton wavelength shift formula and the electron rest mass energy. [2]

a) Explain the phenomenon of pair production and state the energy requirements for it to occur. [3]

b) A gamma-ray photon interacts with the nucleus of an atom and produces an electron-positron pair. If the rest mass energy of an electron is 0.511 MeV, calculate the minimum energy of the gamma-ray photon required for this process. [2]

a) Describe the significance of the work function in the context of the photoelectric effect. [2]

b) A metal has a work function of 4.2 eV. Calculate the threshold frequency for this metal. [3]

c) If light of frequency 1.5 x 10^15 Hz is incident on this metal, will photoemission occur? Justify your answer. [2]

a) Explain the concept of stopping potential in the photoelectric effect. [2]

b) Light of frequency 8 x 10^14 Hz is incident on a metal surface, causing photoemission. If the stopping potential is measured to be 1.5 V, determine the work function of the metal in eV. [3]

c) How would the stopping potential change if the frequency of the incident light is increased? [2]