Question

1) Is light a ray, a wave or particle? Comment.

Answer 1

Light has a dual nature. It acts as a wave and particle in different cases.
Light is a particle because:
1. It travels in straight lines;
2. It forms sharp shadows;
3. Light beams are localized in space;
4. It was easier to imagine a stream of particles traveling in a vacuum


Reflection and refraction of light were easily understood using particle model, (although the model for refraction turned out to be wrong in detail even though it explained the general observations).
Light is a wave because:
1. Two crossing beams do not collide.
2. Light beams travel at only one speed.