Two thin lenses with f₁=+30 cm and f₂=-40 cm are in contact. Determine the equivalent focal length.
Options

Question

Two thin lenses with f₁=+30 cm and f₂=-40 cm are in contact. Determine the equivalent focal length.

G1 Physics · Accepted Answer

1/F=1/f₁+1/f₂, so F=120.00 cm.