Question

Find the power of a concave lens of focal length 20 m​

Answer 1

Answer:

ExplanGiven that, Focal length of a concave lens, f = -20 cm = 0.2 m (negative for concave lens.

To find, Power of a lens.

Solution, Let P is the power of concave lens. Power of a lens is reciprocal of its focal length. It is given by :

So, the power of a concave lens is (-5 D).

Power of a lens.ation:

Answer 2

Answer:

• Given that, Focal length of a concave lens, f = -20 cm = 0.2 m (negative for concave lens.

        To find, Power of a lens.

• Solution, Let P is the power of concave lens. Power of a lens is reciprocal of its focal length. It is given by :

• So, the power of a concave lens is (-5 D).

• Power of a lens.