Electromagnetic Induction — Physics STD 12 Science — Question

The mass of ions deposited during a given interval of time in the process of electrolysis depends on

(a) The current

(b) The resistance

(c) The temperature

(d) The electric power

In a full wave rectifiers, input ac current has a frequency ‘n’. The output frequency of current is

(a) n/2

(b) n

(c) 2n

(d) None of these

In hydrogen atom, an electron is revolving in the orbit of radius 0.53  with 6.6  rotations/second. Magnetic field produced at the centre of the orbit is

(a) 0.125

(b) 1.25

(c) 12.5

(d) 125

Mark the correct statements:

1. The magnitude of the velocity of a particle is equal to its speed.
2. The magnitude of average velocity in an interval is equal to its average speed in that interval
3. It is possible to have a situation in which the speed of a particle is always zero but the average speed is not zero.
4. It is possible to have a situation in which the speed of the particle is never zero but the average speed in an interval is zero.

Two long parallel wires are at a distance 2d apart. They carry steady equal currents flowing out of the plane of the paper, as shown. The variation of the magnetic field B along the line XX’ is given by

(a)

(b)

(c)

(d)

The magnetic force required to demagnetise the material is:

A coil develops heat of 800 cal/sec. When 20 volts is applied across its ends. The resistance of the coil is (1 cal = 4.2 joule)

(a) 1.2 Ω

(b) 1.4 Ω

(c) 0.12 Ω

(d) 0.14 Ω

In the middle of the depletion layer of a reverse-biased PN junction, the

(a) Potential is zero	(b) Electric field is zero
(c) Potential is maximum	(d) Electric field is maximum

Chadwick was awarded the 1935 nobel prize in physics for his discovery of the:

Which among the following is the source of the magnetic field (magnetism)?