Though a direct question it was fairly well attempted by most responding candidates. Few candidates could hardly remember the conditions for the emission of photoelectrons or the particle characteristics of e-m waves.
The expected answers are:
(a) Conditions for emission of photoelectrons
- the wavelength of incident radiation must be less than the threshold wavelength of
metal surface
- the frequency of incident radiation must be greater than the threshold frequency.
- the energy of the incident photons (radiation) must be greater than the
Work function of the metal
(b) Particle characteristics of electromagnetic waves
e.g - Photoelectric effect
- Thermionic emission
- Radiations from heated bodies (Black body)
- Emission and absorption of light (incandescence).
- Compton effect.