Question

When a convex lens is placed above an empty tank, the image of a mark at the bottom of the tank, which is 45 cm from the lens is formed 36 cm above the lens. When a liquid is poured in the tank to a depth of 40 cm, the distance of the image of the mark above the lens is 48 cm. The refractive index of the liquid is:

• A. 1.353
• B. 1.544
• C. 1.472
• D. 1.366

Hint:

To calculate the refractive index of a medium, use the lens formula to determine the focal length in both air and the medium, then take their ratio.