Question

Why does only transparent bodies allow light to pass through them?

Answer 1

When light waves strike an object three things may happen. The light can be reflected, absorbed or it may change its direction.

What happens to light depends on the kind of object or material that it hits.

Transparent objects, like glass, let light waves pass through without mixing them up. transparency is basically the physical property of allowing light to pass through the material without being scattered. On a macroscopic scale (one where the dimensions investigated are much, much larger than the wavelength of the photons in question), the photons can be said to follow Snell's Law.