Question

Question 1
4
An object is located 90 m in front of a lens. An image is produced 40 m away from the
lens. What is the focal length of the lens?
O 15.3 m
0.025 m
O 27.7 m
O .011 m

Answer 1

1/f= 1/di+1/do
1/f=1/90m+1/40m
1/f ≈27.7m