Electromagnetic Induction Physics - Electromagnetic Induction

Consider the following statements:

1. An emf can be induced by moving a conductor in a magnetic field.
2. An emf can be induced by changing the magnetic field.

1. Both A and B are true.
2. A is true but B is false.
3. B is true but A is false.
4. Both A and B are false.

Consider the situation shown in figure. If the switch is closed and after some time it is opened again, the closed loop will show:

1. An anticlockwise current-pulse.
2. A clockwise current-pulse.
3. An anticlockwise current-pulse and then a clockwise current-pulse.
4. A clockwise current-pulse and then an anticlockwise current-pulse.

A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field. An emf is induced in the loop if:

1. It is translated.
2. It is rotated about its axis.
3. It is rotated about a diameter.
4. It is deformed.

A small, conducting circular loop is placed inside a long solenoid carrying a current. The plane of the loop contains the axis of the solenoid. If the current in the solenoid is varied, the current induced in the loop is:

1. Clockwise.
2. Anticlockwise.
3. Zero.
4. Clockwise or anticlockwise depending on whether the resistance in increased or decreased.

A metal sheet is placed in front of a strong magnetic pole. A force needed to:

1. Hold the sheet there if the metal is magnetic.
2. Hold the sheed there if the metal is nonmagnetic.
3. Move the sheet away from the pole with uniform velocity if the metal is magnetic.
4. Move the sheet away from the pole with uniform velocity if the metal is nonmagnetic. Negative any effect if oaramagnetism, diamagnetism and gravity.

Two circular loops are placed with their centres separated by a fixed distance. How would you orient the loops to have:

1. The largest mutual inductance.
2. The smallest mutual inductance?

Consider the energy density in a solenoid at its centre and that near its ends. Which of the two is greater?

Consider the self-inductance per unit length of a solenoid at its centre and that near its ends. Which of the two is greater?

A metallic metre stick moves with a velocity of 2m/s^-1 in a direction perpendicular to its length and perpendicular to a uniform magnetic field of magnitude 0.2 T. Find the emf induced between the ends of the stick.

If the magnetic field outside a copper box is suddenly changed, what happens to the magnetic field inside the box? Such low-resistivity metals are used to form enclosures which shield objects inside them against varying magnetic fields.

An inductor-coil carries a steady-state current of 2.0A when connected across an ideal battery of emf 4.0V. If its inductance is 1.0H, find the time constant of the circuit.

Figure shows a circular wheel of radius 10.0cm whose upper half, shown dark in the figure, is made of iron and the lower half of wood. The two junctions are joined by an iron rod. A uniform magnetic field B of magnitude 2.00 × 10^-4 T exists in the space above the central line as suggested by the figure. The wheel is set into pure rolling on the horizontal surface. If it takes 2.00 seconds for the iron part to come down and the wooden part to go up, find the average emf induced during this period.

Consider a small cube of volume 1mm³ at the centre of a circular loop of radius 10cm carrying a current of 4A. Find the magnetic energy stored inside the cube.

A wire-loop confined in a plane is rotated in its own plane with some angular velocity. A uniform magnetic field exists in the region. Find the emf induced in the loop.

The current generator I_g shown in figure, sends a constant current i through the circuit. The wire cd is fixed and ab is made to slide on the smooth, thick rails with a constant velocity v towards right. Each of these wires has resistance r. Find the current through the wire cd.

The magnetic field at a point inside a 2.0mH inductor coil becomes 0.80 of its maximum value in 20µs when the inductor is joined to a battery. Find the resistance of the circuit.

A circular copper-ring of radius r translates in its plane with a constant velocity v. A uniform magnetic field B exists in the space in a direction perpendicular to the plane of the ring. Consider different pairs of diametrically opposite points on the ring.

1. Between which pair of points is the emf maximum? What is the value of this maximum emf?
2. Between which pair of points is the emf minimum? What is the value of this minimum emf?

A metallic loop is placed in a nonuniform magnetic field. Will an emf be induced in the loop?

A wire of length 10cm translates in a direction making an angle of 60° with its length. The plane of motion is perpendicular to a uniform magnetic field of 1.0T that exists in the space. Find the emf induced between the ends of the rod if the speed of translation is 20cm/s^-1.

A conducting square loop having edges of length 2.0cm is rotated through 180° about a diagonal in 0.20s. A magnetic field B exists in the region which is perpendicular to the loop in its initial position. If the average induced emf during the rotation is 20mV, find the magnitude of the magnetic field.

The current in a discharging LR circuit without the battery drops from 2.0A to 1.0A in 0.10s.

1. Find the time constant of the circuit.
2. If the inductance of the circuit is 4.0H, what is its resistance?

A bicycle is resting on its stand in the east-west direction and the rear wheel is rotated at an angular speed of 100 revolutions per minute. If the length of each spoke is 30.0cm and the horizontal component of the earth's magnetic field is 2.0 × 10^-5 T, find the emf induced between the axis and the outer end of a spoke. Neglect centripetal force acting on the free electrons of the spoke.

A right-angled triangle abc, made from a metallic wire, moves at a uniform speed v in its plane as shown in figure. A uniform magnetic field B exists in the perpendicular direction. Find the emf induced:

1. In the loop abc.
2. In the segment bc.
3. In the segment ac.
4. In the segment ab.