Question

if the radius of curvature is 20cm the distance of focus will be​

Answer 1

Answer:

f=r÷2

=20÷2

=10cm

10cm is the answer.

Answer 2

Explanation:

R = 2f

So, we change the cm in m.

Then 20 cm = 0.4 m

So put the value -

F= 0.4 m ans.