there is a cylindrical tube of length (30 cm)and having its inner lateral surface blackened.two lenses of focal length 10 cm and 20 cm are taken.and are fixed at the both ends of the tube.if we pass same beams of light first from the side of 10 cm lens ,and then from 20 cm lens .now the intensity of light on a spot on the screen on the other side in case of 1 st is I1 and for 2nd I2.then I1/I2=

1> 1/16

2> 16

3>1

4>1/4

5>4

swaraj jena , 15 Years ago

Grade 12