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 100 mH coil carries a current of 1 A. Energy stored in the magnetic field is
0.5 J
1 J
0.1 J
0.05 J
A long solenoid has 800 turns per metre length of solenoid. A current of 1.6A flows through it. The magnetic induction at the end of solenoid is
0.8 x 10-3 T
16 x 10-4 T
32 x 10-4 T
4 x 10-4 T
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
If a current is passed through a spring, then the spring
expands
gets compressed
remains same
None of these
A circuit has a self inductance of 1 H and carries a current of 2 A. To prevent sparking when the circuit is broken, a capacitor which can withstand 400 V is used. The capacitance of the capacitor is
25 μF
125 μF
100 pF
50 μF
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 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
The inductance of a coil is directly proportional to
its length
the number of turns
the resistance of the coil
the square of the number of turns
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
