Question

19. An object is placed 20 cm from a convex mirror. If a virtual image appears 5 cm from the mirror on the other side of the mirror from the object, what is the focal length of the mirror? Also, draw a ray tracing diagram.

Answer 1

I did the ray-tracing diagram and got that part correct, but I got the focal length wrong. I got 4 cm. If someone could review and include the steps that would be great.

Answer 2

@DuarteME

Answer 3

I don't get what I did wrong? I used the focal length equation, got object distance as 20 cm and image distance as 5 cm, then what did I do wrong?

\(\frac{1}{f}=\frac{1}{20}+\frac{1}{5}\)
f=4

Answer 4

Nvm, I figured it out

it's a virtual image so it would be 1/20 - 1/5