Question

Two thin lenses of power 3D and -2D are placed in contact, then power and focal length of the lens combination is *
a) +2D , +100cm
b) +1D, +100cm
c) +5D , +20cm
d) +1D , -100cm

please answer fast

Answer 1

Answer:

Option (b)

Explanation:

Power of combination Peff = P1+ P2 = 3D + (-2D) = +1D

Focal length (in cm) = 100/power = 100/+1D = +100cm

Hope you understood the answer :)