# Geometric Optics: Bird and Fish Problem

A bird in air is diving vertically over a tank with speed 6 cm/s. Base of tank is silvered. A fish in the tank is rising upward along the same line with speed 4 cm/s. Water level is falling at rate of 2 cm/s. (Refractive index of water = 4/3)

Column â€“ I Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â Column â€“ II

(A) The speed of the image of the fish as seen by the bird directly Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â (p) 12

(B) The speed of the image of fish formed after the reflection from the mirror as seen by the bird (q) 4

(C) The speed of the image of the bird relative to the fish looking upwards Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  (r) 9

(D) The speed of the image of the bird relative to the fish looking downward in the mirror Â  Â  Â  Â  Â  Â  Â  (s) 3

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