Question

3. A cylindrical container is 20 cm deep. Water v=4/3 is filled in the container upto the brime. By how
many centimaters will its bottom appear as raised up.
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Answer 1

☆Concept:

• The image formed of the bottom surface will be seen as raised above due to the phenomena of refraction.

• The main thing here is to carefully apply the formula of apparent depth.

☆Formula

$\boxed{\sf d_{app} = \dfrac{d}{\dfrac{\mu_{object}}{\mu_{observer}}}}$

here, $\mu$ is the refractive index of the medium.

☆Solution

•First see the attached figure.

•$\mu_{object} = water =\dfrac{4}{3}$

•$\mu_{observer} = air = 1$

》Warning: here apparent depth is measured from the top surface.

•Now put the values in formula:

$\longrightarrow\sf d_{app} = \dfrac{20}{\dfrac{4/3}{1}}$

$\longrightarrow\sf d_{app} = \dfrac{20\times 3}{4}$

$\longrightarrow\bf d_{app} = 15\: cm$

☆This is measure from above top surface of water.

☆☆So, bottom surface will be raised by 15 cm from top and 5 cm from bottom.