Question

The focal length of a convex lens is 20cm. What is its power? (5D) *​

Answer 1

Answer:

$power = \frac{1}{focal \: length \: (in \: metres) } \\ = \frac{1 \times 100}{20} \\ = 5 \: dioptre$

which is the required ans

Answer 2

Answer:

Power = 5D

Explanation:

Power = 1/focal length(in m)

Here, f = 20 cm

= 0.2 m

Power = 1/0.2

= 5 D