Figure below shows a lens of refractive index, μ = 1.4. C1 and C2 are the centres of curvature of the two faces of the lens of radii of curvature 4 cm and 8 cm respectively.
The lens behaves as a
1
diverging lens of focal length 20 cm
2
converging lens of focal length 20 cm
3
converging lens of focal length 12 cm
4
diverging lens of focal length 12 cm