A tank is filled with water to a height of 12.5 cm. The apparent depth of a needle lying at the bottom of the tank is measured by a microscope to be 9.4 cm. What is the refractive index of water? If water is replaced by a liquid of refractive index 1.63 up to the same height, by what distance would the microscope have to be moved to focus on the needle again?
Apparentdepth=μRealdepth where, μ= refractive index => μ=ApparentdepthRealdepth Given, real depth = 12.5 cm apparent depth = 9.4 cm => μ=9.412.5=1.329 CASE 2: If real depth is 1.63, then => apparentdepth(needle)=1.6312.5=7.669cm => The needle shifted =9.4−7.669=1.731cm upwards
