Question

Which property of light is involved
in the formation of shadow ?
Explain in which case you will not
get penumbra at all.​

Answer 1

Answer:

I think rectilinear propagation of light. A "penumbra" is that region around the umbra where the shadow is only partial, or imperfect. You get these when the light source is larger than a single point. These form because while some of the light from the source gets blocked by the shadowing object, not all of it does