Electromagnetic Induction — Physics STD 12 Science — Question

In Fig., assuming the diodes to be ideal:

A straight conductor of length 0.4 m is moved with a speed of 7 m/s perpendicular to the magnetic field of intensity of 0.9 Wb/m². The induced e.m.f. across the conductor will be

(a) 7.25 V

(b) 3.75 V

(c) 1.25 V

(d) 2.52 V

The centre of mass of a system of particles is at the origin. It follows that:

1. The number of particles to the right of the origin is equal to the number of particles to the left.
2. The total mass of the particles to the right of the origin is same as the total mass to the left of the origin.
3. The number of particles on X-axis should be equal to the number of particles on Y-axis.
4. If there is a particle on the positive X-axis, there must be at least one particle on the negative X-axis.
5. None.

A spring-mass system occillates in a car. if the car accelerates on a horizontal road, the frequency of oscillation will:

1. Increase.
2. Decrease.
3. Remain same.
4. Become zero.

The speed of electromagnetic wave in vacuum depends upon the source of radiation

(a) Increases as we move from g-rays to radio waves

(b) Decreases as we move from g-rays to radio waves

(c) Is same for all of them

(d) None of these

Find the equivalent resistance across AB

(a) 1 W

(b) 2 W

(c) 3 W

(d) 4 W

Suppose all the surfaces in the previous problem are rough. The direction of friction on B due to A:

1. Is upward.
2. Is downward.
3. Is zero.
4. Depends on the masses of A and B.

The minimum wavelength of X-ray emitted by X-rays tube is 0.4125 Å. The accelerating voltage is

(a) 30 kV

(b) 50 kV

(c) 80 kV

(d) 60 kV

The ratio of amplitude of a magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to:

Three capacitors of capacity   are connected in series. Their total capacity will be

(a)	(b) 1/
(c) (	(d) None of these