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JEE Main 2023 (11 Apr, Shift 2) · Refraction, Glass Slab & Apparent Depth

Refraction, Glass Slab & Apparent Depth question from JEE Main 2023 (11 Apr, Shift 2)

Q43JEE Main 2023 · 11 APR · SHIFT 2Difficult

Refraction, Glass Slab & Apparent Depth

As shown in the figure, a plane mirror is fixed at a height of 50 cm50\text{ cm} from the bottom of tank containing water (μ=43)\left(\mu = \frac{4}{3}\right). The height of water in the tank is 8 cm8\text{ cm}. A small bulb is placed at the bottom of the water tank. The distance of image of the bulb formed by mirror from the bottom of the tank is ___________ cm\text{cm}.

Figure

Numerical answer type. Work it out, then open the answer.

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Answer: 98

  1. The bulb seen from above appears at depth 84/3=6 cm\frac{8}{4/3} = 6\text{ cm} below the water surface, i.e. 2 cm2\text{ cm} above the bottom.
  2. This apparent bulb is the object for the mirror: distance from mirror =50−2=48 cm= 50 - 2 = 48\text{ cm}.
  3. Plane mirror image is 48 cm48\text{ cm} behind (above) the mirror: 50+48=98 cm50 + 48 = 98\text{ cm} from the bottom.
  4. So the image is 98 cm98\text{ cm} from the bottom.
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