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

Explanation

As shown in figure, the bottom of tank is at `h_2` depth in denser medium (water) of refractive index `n_2=n`.

When the bottom is viewed normally, it is observed at O. instead of O as shown in figure (a).
When it is viewed at some angle from normal, it is observed at O. as shown in figure (b).
Real depth is `h_2` and apparent depth is `h_1`.
`therefore ("refractive index of air "n_1)/("refractive index of denser medium "n_2)`
`therefore 1/n = h_1/h_2 [therefore "For air "n_1=1]`
`therefore n=h_2/h_1=("real depth")/("apparent depth")`
`therefore` Apparent depth `h_1=("real depth "h_2)/("refractive index of denser medium n")`
Remember : `("n(denser)")/("n(rarer)")=("apparent depth")/("real depth")`