Question

A student is finding the focal length of the concave mirror by focusing a distant tree on a
wall as a screen. If the distance between the wall and the mirror is 10cm then the focal
length is
a) 20cm b)5cm
c)10cm d)Can't determine​

Answer 1

Answer:

5 cm...10/2=5.. ... f=R/2 So f=10/2=5cm