The focal length of the lens on the photo camera is 5cm. What is the power of the lens?
A. +5 D
B. +10 D
C. +15 D
D. +20 D
Answer:D
The focal length of the lens on the photo camera is 5cm. What is the power of the lens?
A. +5 D B. +10 D C. +15 D D. +20 D