Moving Charges and Magnetism — Physics STD 12 Science — Question

A plane electromagnetic wave of frequency 20 MHz travels through a space along x direction. If the electric field vector at a certain point in space is 6V m^-1, what is the magnetic field vector at that point?

Venus appears brighter than other stars because

(a) It is heavier than other planets

(b) Its density is more than other planets

(c) It is nearer to earth in comparison to other planets

(d) Nuclear fusion takes place at its surface

A varying current at the rate of 3 A/s in a coil generates an e.m.f. of 8 mV in a nearby coil. The mutual inductance of the two coils is

(a) 2.66 mH

(b) 2.66

(c) 2.66 H

(d) 0.266 H

The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is 2 s. The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be

(a) 2 s

(b) 2/3 s

(c) 2

(d) 2/

Consider a collision between an oxygen molecule and a hydrogen molecule in a mixture of oxygen and hydrogen kept at room temperature. Which of the following are pcssible?

1. The kinetic energies of both the molecules increase.
2. The kinetic energies of both the molecules decrease.
3. The Kinetic energy of the oxygen molecule increases and that of the hydrogen molecule decreases.
4. The kinetic energy of the hydrogen molecule increases and that of the oxygen molecule decreases.

A plane electromagnetic wave with a single frequency moves in vacuum in the positive x direction. Its amplitude is uniform over the yz plane. the amplitude of its magnetic field. 

In an endothermic reaction the binding energies of reactants and products are e_1​, e₂​ respectively, then:

Switch S of the circuit shown in figure. is closed at t = 0. If e denotes the induced

emf in L and i, the current flowing through the circuit at time t, which of the following graphs is correct

(a)

(b)

(c)

(d)

A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be: