Physics Test - ...

A charged particle is moving in a uniform magnetic field in a circular path. Radius of circular path is R. What will be new radius, when energy of particle is doubled?

An oil drop having charge 2e is placed stationary between two parallel horizontal plates 2 cm apart when a potential difference of 12000 volts is applied between them. What will be the radius of the drop, if the density of oil is 900 kg/m3?

A source of e.m.f. E = 15 V and having negligible internal resistance is connected to a variable resistance so that the current in the circuit increases with time as i = 1.2 t + 3. Then, find the total charge that will flow in first 5 second.

When a piece of aluminium wire of finite length is drawn through a series of dies to reduce its diameter to half its original value, then what will be the effect on its resistance?

If a proton, deuteron and α- particle on being accelerated by the same potential difference enters perpendicular to the magnetic field, then find the ratio of their kinetic energies.

2 rods of same material and length have their electric resistance in ratio 1:2. Which of the following will be the correct statement, when both rods are dipped in water?

The figure shows, three charges Q, (+q) and (+q) that are situated at the vertices of an equilateral triangle of side 'l'. If the net electrostatic energy of the system is zero, then evaluate Q.

A particle has 'a' mass 400 times than that of the electron and charge is double than that of a electron. It is accelerated by 5V of potential difference. Initially the particle was at rest, then what will be its final kinetic energy?

A piece of wire of resistance 4 ohms is bent through 180^o at its mid-point and two halves are twisted together, then what is its resistance?

In a wire of circular cross-section with radius r, free electrons travel with a drift velocity V when a current I flows through the wire. When the drift velocity is 2V, then how much is the current in another wire of half the radius and of the same material?