Question

which property of light makes shadow?

Answer 1

Whenever light(and waves in general) reach an obstacle, they bounce off. Shadows appear simply because, the light that was falling on that area or spot is being shielded. We see shadows because, there is more light in the surroundings that than there is light at the shadow area.

Answer 2

Opaque object nahi the shadow when the light are travelling in a straight line