Question

5. How far would an object need to be placed from a mirror of focal length 10.0 cm if it is
image which is 20.0 cm BEHIND the mirror?
Insert your solution here:​

Answer 1

Answer:

it will be 20/3Part 1: v=+20 f=+10 u=???

1/u + 1/v = 1/f

I/u = 1/f - 1/v = 1/10 - 1/20 = 1/20

u = 20 cm

Part 2: v=-20, f=+10 u=???

1/u = 1/f - 1/v = 1/10 + 1/20 = 3/20

u = 20/3