Question

How does light able to pass through a glass slab but not through any other opaque object like the human body?

What makes glass slab so unique that it allows light to pass through?

Answer 1

Electromagnetic wave (propagation of an oscillating electric and magnetic field) passing through a transparent medium like glass busily polarizes and magnetizes all the molecules on its way. The resulting oscillating dipoles create their own oscillating electric and magnetic field. Hence, the EM wave propagates through a transparent medium. In case of an opaque medium, the EM wave generated by the oscillating dipoles of the medium is damped and is lost (absorbed by the medium) in the medium.