A current carrying solenoid contains an iron rod inside it. A current flows in the solenoid due to a DC source, of constant emf, connected across the ends of the solenoid. When the rod is pulled out of the solenoid, then the current in the solenoid will
Increase
Decrease
Remain constant
Becomes zero
A rectangular coil of 20 turns and area of cross-section 25 cm2 has a resistance of 100 Ω. If a magnetic field which is perpendicular to the plane of the coil changes at the rate of 1000 T per second, the current in the coil is
1A
50 A
0. 5 A
5 A
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
A magnet is allowed to fall through a metallic ring. During fall, its acceleration is
less than g
equal to g
greater than g
equal to 2g
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
0.01 s
The magnetic flux linked with a coil is given by the equation : Φ = 5 t2 + 3 t + 6. The induced e.m.f. in the coil in the fourth second will be
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
When the current changes from +2 A to -2 A in 0.05 s, and emf of 8V is induced in the coil. Calculate the coefficient of self-induction of the coil ?
0.2H
0.4H
0.8H
0.1H
A long solenoid has 200 turns/cm and carries a current I. The magnetic field at its centre is 5.28 x 10-2 Wbm-2. Another long solenoid has 100 turns/cm and it carries a current I/3. The value of the magnetic field at its centre is
1.05 x 10-2 Wb m-2
1.05 x 10-5 Wb m-2
1.05 x 10-3 Wb m-2
1.05 x 10-4 Wb m-2
A coil of area 100 cm2 has 500 turns. Magnetic field of 0.1 Wb/m2 is perpendicular to the coil. The field is reduced to zero in 0.1s. The induced e.m.f. in the coil is
5 V
1 V
50 V
