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Solve question 10

Q.10. How much water would be filled in a container of height 21 cm, so that it appears half filled to the observer when viewed from the top of the container? (${\mu}_{W}$ = 4/3)

so the real depth of container = h, and apparent depth of water =21-h

real depth /apparent depth = refractive index of water

$\frac{h}{21-h}=\frac{4}{3}\phantom{\rule{0ex}{0ex}}3h=4\times 21-4h\phantom{\rule{0ex}{0ex}}3h+4h=4\times 21\phantom{\rule{0ex}{0ex}}7h=4\times 21\phantom{\rule{0ex}{0ex}}h=12cm$

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