When a ray of light travel from glass to air, then deviation of ray is

1. i - r
2. zero
3. r - i
4. 90°

Which of the following colours has more lateral displacement?

1. Red
2. Blue
3. Green
4. Violet

Which of the following is the electrostatic unit of charge?

1. franklin
2. q/m².sec
3. becquerel
4. calorie

A woman pushes a trunk on a railway platform which has a rough surface. She supplies a force of 100 N over a distance of 10 m. Thereafter, she gets progressively tired and her applied force reduces linearly with distance to 50 N. The total distance by which the trunk has been moved is 20 m.

If frictional force between trunk and rough surface is 50 N, then calculate the net work done by the two forces over 20 m.

1. 1000 J
2. 500 J
3. 750 J
4. 1500 J