Question

The power of the combination of two lenses A and B is 5 D. If the focal length of lensA is 15 cm, find the focal length of lens B
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Answer 1

Answer:

f

Explanation:

focal length of combination =1/P=1/5 =0.2m

combination formula 1/f=1/f1+1/f2

1/0.2=1/20cm

1/20=1/15+1/f2

1/20-1/15=1/f2

(3-4)/60 =-1/60cm

f2=-60ck