Class 12 Electromagnetic Induction CBSE Questions & Answers

A metallic rod of 1 m length is rotated with a frequency of 50 rev/s about an axis passing through the centre point O. Other end of the metallic rod slides on a Metallic ring . A constant and uniform magnetic field of 2 T parallel to the axis is present everywhere. What is the emf between the centre and the metallic ring?

A wheel with 10 metallic spokes each 0.5 m long is rotated with a speed of 60 rev/min in a plane normal to the horizontal component of earth’s magnetic field HE at a place. If HE = 0.4 G at the place, what is the induced emf between the axle and the rim of the wheel? Note that 1 G = 10–4 T.

The arm PQ of the rectangular conductor is moved from \({\rm{x }} = {\rm{ }}0\), outwards. The uniform magnetic field is perpendicular to the plane and extends from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ b}}\) and is zero for \({\rm{x }} > {\rm{ b}}\) . Only the arm PQ possesses substantial resistance r. Consider the situation when the arm PQ is pulled outwards from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ 2b}}\) , and is then moved back to \({\rm{x }} = {\rm{ }}0\) with constant speed v. flux and emf for \(0{\rm{ }} \le {\rm{ x }} < {\rm{ b}}\) are

The arm PQ of the rectangular conductor is moved from \({\rm{x }} = {\rm{ }}0\), outwards. The uniform magnetic field is perpendicular to the plane and extends from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ b}}\) and is zero for \({\rm{x }} > {\rm{ b}}\) . Only the arm PQ possesses substantial resistance r. Consider the situation when the arm PQ is pulled outwards from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ 2b}}\) , and is then moved back to \({\rm{x }} = {\rm{ }}0\) with constant speed v. flux and emf for \({\rm{b }} \le {\rm{ x }} < {\rm{ 2b}}\) are

The arm PQ of the rectangular conductor is moved from \({\rm{x }} = {\rm{ }}0\), outwards. The uniform magnetic field is perpendicular to the plane and extends from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ b}}\) and is zero for \({\rm{x }} > {\rm{ b}}\) . Only the arm PQ possesses substantial resistance r. Consider the situation when the arm PQ is pulled outwards from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ 2b}}\) , and is then moved back to \({\rm{x }} = {\rm{ }}0\) with constant speed v. Force necessary to pull the arm and the power dissipated as Joule heat, for \(0{\rm{ }} \le {\rm{ x }} < {\rm{ b}}\) are

The arm PQ of the rectangular conductor is moved from \({\rm{x }} = {\rm{ }}0\), outwards. The uniform magnetic field is perpendicular to the plane and extends from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ b}}\) and is zero for \({\rm{x }} > {\rm{ b}}\) . Only the arm PQ possesses substantial resistance r. Consider the situation when the arm PQ is pulled outwards from \({\rm{x }} = {\rm{ }}0\) to \({\rm{x }} = {\rm{ 2b}}\) , and is then moved back to \({\rm{x }} = {\rm{ }}0\) with constant speed v. Force necessary to pull the arm and the power dissipated as Joule heat, for \(0{\rm{ }} \le {\rm{ x }} < {\rm{ b}}\) are

Two concentric circular coils, one of small radius \({{\rm{r}}_{\rm{1}}}\) and the other of large radius \({{\rm{r}}_{\rm{2}}}\), such that \({\rm{r1 }} < < {\rm{ r2}}\), are placed co-axially with centres coinciding. Mutual inductance of the arrangement is

Expression for the magnetic energy stored in a solenoid in terms of magnetic field B, area A and length l of the solenoid is

Given magnetic field B, area A and length l of a solenoid. The magnetic energy per unit volume is

Kamla peddles a stationary bicycle the pedals of the bicycle are attached to a 100 turn coil of area\(0.{\rm{1}}0{\rm{ }}{{\rm{m}}^{\rm{2}}}\). The coil rotates at half a revolution per second and it is placed in a uniform magnetic field of 0.02 T perpendicular to the axis of rotation of the coil. What is the maximum voltage generated in the coil?

Use Lenz’s law to determine the direction of induced current in the situations described by the Figure (a) A wire of irregular shape turning into a circular shape; (b) A circular loop being deformed into a narrow straight wire. The directions for (a) and (b) respectively are

A long solenoid with 15 turns per cm has a small loop of area 2.0 \({\rm{c}}{{\rm{m}}^{\rm{2}}}\) placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from 2.0 A to 4.0 A in 0.1 s, what is the induced emf in the loop while the current is changing?

A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is 1 cm \({{\rm{s}}^{ - {\rm{1}}}}\) in a direction normal to the longer side. For how long does the induced voltage last?

A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is 1 cm \({{\rm{s}}^{ - {\rm{1}}}}\) in a direction normal to the shorter side of the loop? For how long does the induced voltage last ?

. A 1.0 m long metallic rod is rotated with an angular frequency of 400 rad \({{\rm{s}}^{ - {\rm{1}}}}\) about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of 0.5 T parallel to the axis exists everywhere. Emf developed between the centre and the ring is