Electromagnetic Induction

A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil. This can be because

(a) The magnetic field is constant

(b) The magnetic field is in the same plane as the circular coil and it may or may not vary

(c) The magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably

(d) There is a constant magnetic field in the perpendicular (to the plane of the coil) direction

The mutual inductance M₁₂of coil 1 with respect to coil 2

(a) Increases when they are brought nearer

(b) Depends on the current passing through the coils

(c) Increases when one of them is rotated about an axis

(d) Is the same as M₂₁ of coil 2 with respect to coil 1

An emf is produced in a coil, which is not connected to an external voltage source. This can be due to

(a) The coil being in a time varying magnetic field

(b) The coil moving in a time varying magnetic field

(c) The coil moving in a constant magnetic field

(d) The coil is stationary in external spatially varying magnetic field, which does not change with time

A metal plate is getting heated. It can be because

(a) A direct current is passing through the plate

(b) It is placed in a time varying magnetic field

(c) It is placed in a space varying magnetic field, but does not vary with time 

(d) A current (either direct or alternating) is passing through the plate

The self inductance L of a solenoid of length l and area of cross-section A, with a fixed number of turns N increases as

(a) l and A increase                                 

(b) l decreases and A increases

(c) l increases and A decreases             

(d) both l and A decrease

Same as problem 4 except the coil A is made to rotate about a vertical axis (figure). No current flows in B if A is at rest. The current in coil A, when the current in B (at t = 0) is counter-clockwise and the coil A is as shown at this instant, t = 0, is

(a) Constant current clockwise

(b) Varying current clockwise

(c) Varying current counter clockwise

(d) Constant current counter clockwise

There are two coils A and B as shown in figure. A current starts flowing in B as shown, when A is moved towards B and stops when A stops moving. The current in A is counter clockwise. B is kept stationary when A moves. We can infer that

(a) There is a constant current in the clockwise direction in A

(b) There is a varying current in A

(c) There is no current in A

(d) There is a constant current in the counter clockwise direction in A

A cylindrical bar magnet is Rotated about its axis. A wire is connected from the axis and is made to touch the cylindrical surface through a contact. Then,

(a) A direct current flows in the ammeter A

(b) No current flows through the ammeter A

(c) An alternating sinusoidal current flows through the ammeter A with a time period 2π/ω

(d) A time varying non-sinusoidal current flows through the ammeter A

A loop, made of straight edges has six corners at A(0,0,0),B(L,0,0),C(L,L,O),D(0,L,0),E(0,L,L)and F(0,0,L). A magnetic field B =B_o(i+K)T is present in the region. The flux passing through the loop ABCDEFA (in that order) is

A square of side L meters lies in the x-y plane in a region, where the magnetic field is given by B=B₀(2i+3j+4k)T, where Bo is constant. The magnitude of flux passing through the square is

(a) 2 Bo L²

(b) 3 Bo L² Wb

(c) 4 Bo L² Wb

(d) B₀L² Wb