Question

Two lenses of power -3.5 D and + 10 are placed in contact Find the total power of the combination of lens Calculate the focal length of this combination​

Answer 1

P = P1+P2

P = -3.5+10

P = 6.5 D

focal length = 1/P

f = 1/P = 1/6.5

f = 0.153 m

or f = 15.3 cm