It is found that photosynthesis starts in certain plants when exposed to the sunlight but it does not start if the plant is exposed only to infrared light. Explain.

When a piece of sodium or potassium are exposed to sunlight ……..

When human body skin get dark when it is exposed to sunlight for longer period of time ?

When exposed to sunlight, thin films of oil on water often exhibit brilliant colours due to the phenomenon of .....

A ball, intially at the top of the inclined hill, is allowed to roll down. At the bottom its speed is 4 m/s. Next the ball is again rolled down the hill, but this time it does not start from rest. It has an initial speed of 3 m/s. How fast is it going when it gets to the bottom ?

A screw gauge with a pitch of 0.5 mm and a circular scale with 50 division is used to measure the thickness of a thin sheet of aluminium. Before starting the measurement, it is found that when the two jaws of the screw are brought in constant, 45th division coincides with the main scale line and that the zero of main scale line and that the zero of main scale is barely visible. What is the thickness of the sheet, if the main scale reading is 0.5 mm and 25th division coincides with the main scalel line ?