A torch is left on behind a door. Neha says the light will bend around and reach the corner behind…

Why

Neha's thinking of light like water or sound, which do curl around corners — a fair guess, since we hear people we can't see. But light isn't like that: it travels in straight lines only. It can't steer itself around a door to reach a hidden corner; wherever a solid thing blocks its straight path, the space behind stays dark — that dark patch is exactly what a shadow is. To light that corner you'd have to bounce the beam off something (a mirror, a pale wall) so a NEW straight line reaches it. Test: you can't see around a wall, but hold a mirror at the corner and suddenly you can — the light went straight to the mirror, then straight to you. Light travels straight: it won't bend around the door by itself, which is why hidden corners stay dark until light is redirected to them.