Question

When an extended source of light moves towards a stationary opaque body, where the extended source is bigger than the opaque body, then on a stationary screen placed behind the object the

• A. penumbra and umbra, both decreases
• B. penumbra and umbra, both increases
• C. penumbra increases and the umbra decreases
• D. penumbra decreases and the umbra increases

Answer 1

The correct option is C

penumbra increases and the umbra decreases

1. Penumbra is the state of partial darkness while umbra is of complete darkness.
2. When an extended source of light moves towards a stationary opaque body, where the extended source is bigger than the opaque body, then on a stationary screen placed behind the object the penumbra increases, and the umbra decreases.

Thus, the correct option is (c).