Question #631d7

1 Answer
A08
Apr 18, 2017

6.bar6cm

Explanation:

When two thin convex lenses of focal length f_1 and f_2 are placed at a distance d apart, the equivalent focal length F of the system is given by the expression

F=(f_1cdotf_2)/(f_1+f_2-d)

Inserting given values we get
F=(20cdot5)/(20+5-10)
F=100/15=6.bar6cm

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