Question

The power of a convex lens of focal length 25 cm is ______.

विकल्प

• 4.0 D

• 0.25 D

• −4.0 D

• −0.25 D

Answer 1

The power of a convex lens of focal length 25 cm is 4.0 D.

Explanation:

Focal length of the convex lens (f) = 25 cm = 0.25 m

Power of the lens is given by the formula

Power = `1/("f"("in meters"))`

P = `1/0.25`

P = 4 D

For a convex lens, the power of the lens is positive.

Therefore the power of the lens is +4 D.