World Geography Questions (MCQs) for UPSC, State PCS & SSC Examinations
Q. What is the focal length of a concave lense with number -5D?
a. 5 cm
b. 10 cm
c. 15 cm
d. 20 cm
The focal length is the distance from the center of the lens to the principal foci (or focal points) of the lens. For a while diverging lenses always have negative focal lengths. The focal length for 5D lens in 20cm.
