Question

a glass jar has plane inner surface pq of its bottom silvered and contains water (of refractive index n=4/3)column of height t=6cm. a small light emitting diode is arranged at o a height d=8cm from the water surface AB. the silvered bottom of the jar acts as a plane mirror.at what distance from the free surface of water will this plane mirror from the image of the light emmiting diode.​

Answer 1

Answer:

From the free surface of water the image of the light emmiting diode will be at distance 17 cm

Explanation:

The diagram is attached

If the refractive index of water w.r.t. air is n then

$\boxed{n=\frac{\text{Real Depth}}{{\text{Apparent Depth}}}}$

Real depth = 6 cm

n = 4/3

Therefore the apparent depth of the mirror PQ

$=6\times\frac{3}{4}$

$=4.5$ cm

Thus, the apparent plane mirror P'Q' is at 4.5 cm from the surface of water.

The diode is at 8 cm from the water surface

Therefore, distance of diode from P'Q' = 8 + 4.5 = 12.5 cm

The image will be formed at distance 12.5 cm behind the plane mirror P'Q'

Therefore, the distance of the image from the water surface = 12.5 + 4.5 = 17 cm

Hope this helps.