question_answer 3)

A tank is filled with water to a height of 12'5 cm. The apparent depth of the needle lying atthe bottom of the tank is measured by amicroscope to be 9-4 cm. What is the refractive index of water? If water is replaced by a liquidof refractive index 6.3 upto the same height,by what distance would the microscope have tobe moved to focus on the needle again ?  

Answer:

Aswe get,                 or If water is replaced by liquid, then So apparent depth Distance through which the microscope has to be moved