Electric Charges and Fields — Physics STD 12 Science — Question

The electric potential at a point on the equatorial line of an electric dipole is:

The motion of a torsional pendulum is:

1. Periodic.
2. Oscillatory.
3. Simple harmonic.
4. Angular simple harmonic.

Consider the situation of the previous problem. The force on the central charge due to the shell is:

A magnet of magnetic moment 2  is aligned in the direction of magnetic field of 0.1 T. What is the net work done to bring the magnet normal to the magnetic field

(a) 0.1  J

(b) 0.2 J

(c) 1 J

(d) 2 J

A particle of mass m and charge q enters a magnetic field B perpendicularly with a velocity v. The radius of the circular path described by it will be:

The reading of a high resistance voltmeter when a cell is connected across it is 2.2 V. When the terminals of the cell are also connected to a resistance of 5Ω the voltmeter reading drops to 1.8 V. Find the internal resistance of the cell

(a) 1.2 Ω

(b) 1.3 Ω

(c) 1.1 Ω

(d) 1.4 Ω

A thick wire is stretched so that its length become two times. Assuming that there is no change in its density, then what is the ratio of change in resistance of wire to the initial resistance of wire

(a) 2 : 1

(b) 4 : 1

(c) 3 : 1

(d) 1 : 4

A resistor  dissipates the power P when connected to a certain generator. If the resistor  is put in series with , the power dissipated by

(a) Decreases

(b) Increases

(c) Remains the same

(d) Any of the above depending upon the relative values of  and

A current of 10 ampere is flowing in a wire of length 1.5 m. A force of 15 N acts on it when it is placed in a uniform magnetic field of 2 tesla. The angle between the magnetic field and the direction of the current is

(a) 30 °

(b) 45 °

(c) 60 °

(d) 90 °