C.O.E. in Induction

Q. A metallic ring connected to a rod oscillates freely like a pendulum. If now a magnetic field is applied in horizontal direction so that the pendulum now swings through the field, the pendulum will

1. Keep oscillating with the old time period
2. Keep oscillating with a smaller time period
3. Keep oscillating with a larger time period
4. Come to rest very soon

Q. In the figure, the switch $S$ is closed so that a current flows in the iron-core inductor which has inductance $L$ and the resistance $R$. When the switch is opened, a spark is obtained in it at the contacts. The spark is due to

1. a slow flux change in $L$
2. a sudden increase in the emf of the battery $B$
3. a rapid flux change in $L$
4. a rapid flux change in $R$

Q.

A conducting ring is placed around the core of an electromagnet as shown in fig. When key K is pressed, the ring

1. Remain stationary

2. Is attracted towards the electromagnet

3. Jumps out of the core

4. None of the above

Q.

A conducting ring is placed around the core of an electromagnet as shown in fig. When key K is pressed, the ring

1. Remain stationary

2. Is attracted towards the electromagnet

3. Jumps out of the core

4. None of the above

Q.

A conducting ring is placed around the core of an electromagnet as shown in fig. When key K is pressed, the ring

1. Remain stationary

2. Is attracted towards the electromagnet

3. Jumps out of the core

4. None of the above