Question

Assertion (A): A point object is placed at a distance of 26 cm from a convex mirror of focal length 26 cm. The image will not form at infinity.

Reason (R): For above given system the equation `1/f = 1/v + 1/u` gives v = ∞.

विकल्प

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

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

• A is true but R is false.

• A is false but R is true.

Answer 1

A is true but R is false.

Explanation:

Given, f = + 26 cm, and u = – 26 cm

Using mirror formula,

`1/f = 1/v + 1/u`

⇒ `1/26 = 1/v - 1/26`

⇒ `1/26 + 1/26 = 1/v`

⇒ `2/52 = 1/v`

⇒ v = 13 cm

So, the image is formed at a finite distance behind the mirror, not at infinity. Hence, the assertion is correct, but the reason is incorrect, as the formula does not give v = ∞.