Question

Two thin convex lens of power 40 and 60 are placed coaxially at a distance of 20 cm apart find the focal length and power of the combination of lenses

Answer 1

p1 = 40

f1 = 1/40

p2 = 60

f2 = 1/60

we know that 1/f1 + 1/f2 =1/f

1/f = 40 + 60

    = 100

1/f =p

total power = 100 D