Question

Which of the following phenomena taken together shows dual nature of light?

• A. Photoelectric effect and Black body radiation
• B. Diffraction and reflection
• C. Diffraction and refraction
• D. Photoelectric effect and diffraction

Answer 1

The correct option is D Photoelectric effect and diffraction

Diffraction is the property of radiation to bend when it passes through an aperture or an edge. The bending is possible only if the radiation has a wave nature.

Reflection and refraction show that radiation beams or rays change their direction when incident on a reflective surface or when incident on an optically denser medium. It does not explain the particle nature of the radiations.

The photoelectric effect of radiation says that when a photon of radiation hits a metal surface, if the energy of the photon is more than the threshold energy of the metal, it causes the emission of electrons. This effect depicts radiations as a packet of energy or a particle having one phonon energy.

Hence, the properties of photoelectric effect and diffraction explain the dual nature of radiation.

Hence, option $\left(\text{D}\right)$ is correct.

Why this question? Key concept: This question is very useful in understanding the dual nature of light.