JEE Main 2025 Physics question
A concave-convex lens of refractive index 1.5 and the radii of curvature of its surfaces are 30 cm and 20 cm, respectively. The concave surface is upwards and is filled with a liquid of refractive index 1.3. The focal length of the liquid-glass combination will be
Answer: (1)
Solution
Using lensmaker's formula for liquid lens and glass lens separately, then combining: , so F = 600/11 cm.