Two lens of power are -1.5 and 2.57 D are kept in contact . Find its focus?

Asked by Mohit RaAz | 14th Dec, 2014, 06:58: PM

Expert Answer:

Given:
Power of first lens, P1 = -1.5 D
Power of second lens, P2 = 2.57 D
Therefore,
Power of combination, P = P1 + P2
                                    = (-1.5 + 2.57) D
                                    = 1.07 D
Now,
Focal length of combination, F = begin mathsize 12px style 1 over straight P end style
                                         F = begin mathsize 12px style fraction numerator 1 over denominator 1.07 end fraction straight m end style
                                         F = 0.934 m

Answered by Faiza Lambe | 14th Dec, 2014, 09:44: PM