Question

Read the following statements and choose the correct option.

(A) Only a point source forms a complete umbra.

(B) An extended source of light forms both umbra and penumbra.

• A. Only A is true.
• B. Only B is true.
• C. Both A and B are true.
• D. Both A and B are false.

Answer 1

The correct option is C

Both A and B are true.

Option (A) is true because; when the light comes out from the point source the rays radiate outwards. When light emanates from a point source, the rays radiate outwards from the source and are therefore not parallel. As a result of the complete blockage of light, a shadow is generated. As a result, just umbra is generated as a shadow, with no penumbra.

Option (B) is true because; unlike the point source, the extended source is capable of producing shadow, that shadow has two types an umbra and a penumbra.

Therefore, option (C) is the correct option.