Two concentric coils each of radius equal to 2 cm are placed at right angles to each other. If 3A and 4A are the currents flowing through the two coils respectively. The magnetic induction (in Wb m-2) at the centre of the coils will be
5 × 10-5
12 × 10-5
7 × 10-5
10-5
Two coils have a mutual inductance 0.005 H. The current changes in the first coil according to the equation I = im sin ωt, where im = 10 A and ω = 100 rad s-1. The maximum value of the emf induced in the second coil is
A wheel with 10 spokes each of length L m is rotated with a uniform angular velocity ω in a plane normal to the magnetic field B. The emf induced between the axle and the rim of the wheel is
NωBL2
When 100 V DC is applied across a coil, a current of 1 A flows through it. When 100 V AC of50 Hz is applied to the same coil only 0.5 A flows. The inductance of the coil is
5.5 mH
0.55 mH
55 mH
0.55 H
An aluminium ring B faces an electromagnet A. The current I through A can be altered. Then which of the following statements is correct ?
If I decreases, A will repel B
Whether I increases or decreases, B will not experience any force
If I increases, A will repel B
If I increases, A will attract B