Question

which of the following phenomena provide evidence for the particle theory of light?
a sonar
b the doppler effect
c diffraction
d light refraction
e the photo - electric effect

Explanation:

• Sonar uses sound waves (not related to light's particle theory).
• Doppler Effect for light can be explained by wave or particle, but not unique to particle theory.
• Diffraction is a wave - like property of light.
• Light refraction can be explained by wave theory (change in speed at medium boundaries).
• The photoelectric effect shows that light behaves as particles (photons) as it can eject electrons from a metal surface only when light of sufficient frequency (related to photon energy) is incident, which is a key evidence for the particle theory of light.

Answer:

e. The photo - electric effect