Q7 of 284 Page 261

How is the power of a lens related to its focal length?

Power of lens is reciprocal of its focal length in metres.

P = 1/f


More from this chapter

All 284 →
5

Which type of lens has (a) a positive power, and (b) a negative power ?

 6

Which of the two has a greater power: a lens of short focal length or a lens of large focal length ?

 8

Which has more power : a thick convex lens or a thin convex lens, made of the same glass ? Give reason for your choice.

 9

The focal length of a convex lens is 50 cm. What is its power ?