Question

Assertion (A): A ray of light which is incident normally (or perpendicularly) on a mirror, is reflected back along the same path.

Reason (R): When a ray of light falls perpendicularly, it means that it goes along the ‘normal’ to the mirror surface. The angle of incidence as well as the angle of reflection for such a ray of light are zero, and hence it is reflected back along the same path.

विकल्प

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is correct explanation of the assertion.

Explanation:

Assertion (A) is true because a normally incident ray retraces its path upon reflection off a mirror surface. Reason (R) correctly explains this behaviour using the law of reflection, noting that a perpendicular ray travels directly along the normal. Because the light line merges with the normal line, the angle of incidence drops to zero (i = 0°), which forces the angle of reflection to equal zero (r = 0°) and causes the exact path reversal.