Is the formula "Real depth/Apparent depth `= mu."` valid if viewed from a position quite away from the normal ?

Real and Apparent Depth

Prove that Refractive index= ("real depth")/("apparent depth")

A sphere made of transparent material of refractive index ( mu =3/2 )and of radius 50 cm has a small air bubble 10 cm below the surface. The apparent depth of the bubble if viewed from outside normally is

A sphere made of transparent material of refractive index ( mu =3/2 )and of radius 50 cm has a small air bubble 10 cm below the surface. The apparent depth of the bubble if viewed from outside normally is

A 20 mm thick layer of water (mu=(4)/(3)) floats on a 35 mm thick layer of another liquid (mu=(7)/(5)) in a tank. A small coin lies at the bottom of the tank. Determine the apparent depth of the coin when viewed normally from above the water.

Obtain the relation between the real depth and apparent depth of bottom of tank filled with water when observed from air.

Does the apparent depth of a tank of water change if viewed obliquely ? if so, does the apparent depth increase or decrease ?