Two thin lenses with f₁=+20 cm and f₂=-30 cm are in contact. Determine the equivalent focal length.
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Question

Two thin lenses with f₁=+20 cm and f₂=-30 cm are in contact. Determine the equivalent focal length.

G1 Physics · Accepted Answer

1/F=1/f₁+1/f₂, so F=60.00 cm.