Geometrical OpticsMedium

Question

A ball is dropped from a height of 20 m above the surface of water in a lake. The refractive index of water is 4/3. A fish inside the lake, in the line of fall of the ball, is looking at the ball. At an instant, when the ball is 12.8 m above the water surface, the fish sees the speed of ball as

Options

A.9 m/s
B.12 m/s
C.16 m/s
D.21.33 m/s

Solution

V2ball = 2 × 10 × 7.2
⇒   v = 12 m/s
Ximage of ball = Xball
Vimage of ball = Vball = × 12 = 16 m/s

Create a free account to view solution

View Solution Free
Topic: Geometrical Optics·Practice all Geometrical Optics questions

More Geometrical Optics Questions

The illumination from the sun is greater at noon than in morning because :...A leaf which contains only green pigments, is illuminated by a laser of wavelength 0.6328 μm. It wound appear to be...Two beams of red and violet colours are made to pass separately through a prism (angle of the prism is 60o). In the posi...When a been of light from air enters into the water, the characteristics of light will not be changed, is :...An illuminance of 2.5 × 105 lm/m2 is produced by sun light falling normally on the surface of the earth. The distan...