A coin is placed at the bottom of a glass trough containing water (refractive index = `4/3` ) up to a height 20 cm. At what depth it will appear when it is viewed from air, vertically above the coin. Draw a suitable ray diagram in support of your answer.

Explanation

Given `mu=4/3` real depth = 20 cm
`mu="real depth"/"apparent depth" therefore " Apparent depth" = "real depth"/mu=(20cm)/(4//3)=15cm`