Question

Two coils carrying current in opposite directions are placed coaxially with centres at some finite separation. If they are brought close to each other then current flowing in them should:
A) Decrease
B) Increase
C) Remain same
D) Become zero

Answer 1

Hint: Here in this question we will be using Lenz’s law which states that the induced current will flow in a direction such that it opposes the change that induced current in a coil, as we change the flux through a coil, an e.m.f. is generated that opposes this change.

Complete step by step solution:
According to the right-hand rule, the direction of the magnetic field in both wires is opposite.
Induce repulsive effects when brought. Therefore the currents should increase, so that the pole power increases. So repulsion increases.

Additional Information: Electromagnets are basically coil coils that behave like bar magnets with a separate north and south pole when an electric current passes through the coil. The static magnetic field created by each individual coil loop is combined with its neighbor, which focuses on the combined magnetic field at the center of the coil, like the single wire loop. The resulting static magnetic field with the north pole at one end and a south pole at the other is uniform and much stronger at the center of the coil than at the outside.

Note: The electric current in a circular loop creates a magnetic field that is more concentrated outside the loop than the center of the loop. And the case of multiple ends is called the solenoid and its center is called the center of the solenoid. Since the line element is perpendicular to the unit vector, we take ${\text{sin}}\theta {\text{ = 1}}$ so that we can obtain the value of the magnetic field at the center of the circular loop going forward.
For the magnetic field due to the current carrying coil, we get that as we go away from the centre of the coil, on its axis, the magnitude of the magnetic field reduces. Its value is maximum at the centre of the coil.