A current varying at the rate of 3A/s in a coil generates an e.m.f. of 8mV in a nearby coil. The mutual inductance of hte two coils is
2.66 H
2.66 x 10-3 mH
0.266 H
2.66 mH
The magnetic flux linked with a coil is given by the equation : Φ = 5 t2 + 3 t + 6.Find out the induced e.m.f. in 4 seconds ?
20 V
40 V
10 V
80 V
The magnetic energy in an inductor changes from maximum value to minimum value in 5 ms when connected to an a.c. source. The frequency of the source is
50 Hz
200 Hz
500 Hz
20 Hz
An aircraft has a wing span of 35 m. It is flying horizontally with a speed of 9 ms-1 and the vertical component of earth's magnetic field is 4 x 10-5T. The potential difference between the tips of the wings will be
12.6 V
0.126 V
1.26 V
0.013 V
A coil is wound in a transformer of rectangular cross-section. If all the linear dimensions of the transformer are increased by a factor of 3 and the number of turns per unit length remains the same, the self inductance increases by a factor of
3
9
27
8
A coil of resistance R and inductance L is connected to a battery of e.m.f. E volts. The final current in the coil is
During a current change from 2 A to 4 A in 0.05 second, 8 V of e.m.f. is developed in the coil. The coefficient of self induction is
0.1 H
0.4 H
0.8 H
0.2 H
A magnetic field of 2 x 10-2 T acts at right angles to a coil of area 100 cm2 with 50 turns. The average e.m.f. induced in the coil is 0.1 V when it is removed from the field in t sec. The value of t is
0.1 s
10 s
0.01 s
1s
A coil has an area of 0.05 m2 and has 800 turns. After placing the coil in a magnetic field of strength 4 x 10-5 Wbm-2, perpendicular to the field, the coil is rotated by 90o in 0.1s.The average emf induced is
zero
0.016 V
0.01 V
0.032 V
The current changes from +2 A to -2 A in 0.05 s, and emf of 8V is found induced in the coil.Then the coefficient of self-induction of the coil is :
0.2H
0.4H
0.8H
0.1H
