Which claim shows that electromagnetic radiation acts like a particle rather than a wave?

Question

Light refracts when traveling from one medium to another.

The photoelectric effect shows that light has definite energy.

The double-slit experiment shows that light forms interference patterns.

The mass of light particles can be measured with advanced technology.

Answer 1

The claim that best shows that electromagnetic radiation acts like a particle rather than a wave is:

The photoelectric effect shows that light has definite energy.

The photoelectric effect demonstrates that light can be thought of as being made up of discrete packets of energy called photons. When light of a certain frequency hits a material, it can dislodge electrons from that material, which can only happen if the light reaches a threshold frequency. This effect cannot be explained by wave theory alone, which supports the particle-like behavior of light.