Some magnetic flux is changed from a coil of resistance 10 . As a result, an induced current is developed in it, which varies with time as shown in the figure. The magnitude of change in flux through the coil in Wb is:
1. | 2 | 2. | 4 |
3. | 6 | 4. | None of these |
A 10 H inductor carries a current of 20 A. How much ice at 0°C could be melted by the energy stored in the magnetic field of the inductor?
Latent heat of ice is 2.26 × J/kg .
1. | 0.08 kg | 2. | 8.8 kg |
3. | 0.88 kg | 4. | 0.44 kg |
Two coils of 10 turns each are arranged such that the mutual inductance between them is 150 mH. The magnetic flux linked through one coil when 2 amperes current will flow in another coil, will be:
1.
2.
3.
4.
A square coil ACDE with its plane vertical is released from rest in a horizontal uniform magnetic field of length 2L (figure). The acceleration of the coil is:
1. | less than g for all the time till the loop crosses the magnetic field completely. |
2. | less than g when it enters the field and greater than g when it comes out of the field. |
3. | g all the time. |
4. | less than g when it enters and comes out of the field but equal to g when it is within the field. |
A copper rod of mass m slides under gravity on two smooth parallel rails l distance apart and set at an angle to the horizontal as shown in fig. At the bottom, the rails are joined by a resistance R. There is a uniform magnetic field perpendicular to the plane of the rails. The terminal velocity of the rod is:
1.
2.
3.
4.
When the current in the portion of the circuit shown in the figure is 2 A and increases at the rate of 1 A/s, the measured potential difference 8 V. However, when the current is 2 A and decreases at the rate of 1 A/s, the measured potential difference 4 V. The value of R and L is:
1. | 3 Ω and 2 H respectively |
2. | 3 Ω and 3 H respectively |
3. | 2 Ω and 1 H respectively |
4. | 3 Ω and 1 H respectively |
In the circuit diagram shown in figure, R = 10 \(\Omega\), L = 5 H, E = 20 V and i = 2 A. This current is decreasing at a rate of 1.0 A/s. at this instant will be:
1. | 40 V | 2. | 35 V |
3. | 30 V | 4. | 45 V |
A straight solenoid has 50 turns per cm in primary coil and 200 turns in the secondary coil. The area of cross-section of the solenoid is 4 cm2. Calculate the mutual inductance.
1. 5.0 H
2.
3. 2.5 H
4.
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
Assertion (A): | When a piece of non-metal and a metal are dropped from the same height near the surface of the earth, the non-metallic piece will reach the ground first. |
Reason (R): | Induced current in metal will decrease the acceleration. |
In the light of the above statements choose the correct answer from the options given below:
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
Assertion (A): | Self-inductance is called the inertia of electricity. |
Reason (R): | It is on account of self-inductance that the coil opposes any change in current passing through it. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |