Question

A convex lens of focal length 25cm and a concave lens of focal length 10cm are placed in close contact with each other calculate the lens power of this combination

Answer 1

hi,

here is your answer,

focal length:the distance between the centre of a lens or curved mirror and its focus.

Optical power (also referred to as dioptric power, refractive power, focusing power, or convergence power) is the degree to which a lens, mirror, or other optical system converges or diverges light. It is equal to the reciprocal of the focal length of the device: P = 1/f.

f=25cm convex lens

f=10cm concave lens

power of convex lens=1/f

=1/0.25d

=4.0d

power of concave lens=1/f

=1/-0.10d

= -10d

total power=4.0d-10.0d

= -6.0d

hope it helps u.....