Mention the conditions under which the weight of a person can become zero.

Mention at least three conditions under which weight of a person can become zero.

Mention the condition under which a current can flow in a conductor .

The height above the earth s surface at which the weight of a person becomes 1/4th of his weight on the surface of earth is (R is the radius of earth)

Explain the conditions under which a mirage is seen.

(a) Obtain the condition under which the current flowing in the current detecing device used in the circuit shown in figure, becomes zero. (b) Describe briefly the device, based on the above condition. Draw a circuit diagram for this device and discuss, in brief, how it is used for finding as unknown resistance.

State the conditions under which a force does no work.?

How do we calculate work done by a force ? Write any two conditions under which work done by a force is zero.