Why does the paper strip open up when touched with a charged rod?

A particle with charge q moving with a velocity v in the plane of the paper enters a uniform magnetc field B, acting perpendicular to the plane of the paper. Deduce an expression for the tie period of the charge, as it moves in a circular path in the field. Why does the kinetic energy of the charge not change, while moving in the magnetic field?

Why does the temperature of a gas decrease when it is allowed to expand adiabatically?

Why does nitric oxide become broen when released inn air?

Why does a motor take more current when we start it?

Why does an object float or sink when placed on the surface of water ?

A circuit is connected as shown in the figure with the switch S open. When the switch is closed, the total amount of charge that flows from Y to X is

The frequency of a charge circulating iside the dees of a cyclotron does not depend upon the speed of the charge. Why?