A microscope is focused on an ink mark on the top of a table. If we place a glass slab 3cm thick on it, how should the microscope be moved to focus the ink spot again? The refractive index of glass slab is 1.5 cm.
1 cm upwards
The image of the ink spot moves up by 1cm.
Refractive index = Real depth/ apparent depth
1.5 = 3/ apparent depth
Apparent depth = 3/1.5 = 2 cm
Distance through which the microscope is moved is 3 cm -2 cm = 1 cm upwards