Chapter 20, Problem 26Q

(a)

To determine

The direction of the current moving in the lower wire.

Answer to Problem 26Q

The current in the lower wire would be in the North direction.

Explanation of Solution

Introduction:

According to the right-hand rule, if thumb represents the direction of the current then the direction of magnetic field is indicated by curled fingers.

The current in the lower wire must be in the opposite direction as compared with the direction of the current in the upper wire. If the direction of current in the upper wire is in the South direction then using the right-hand rule, the magnetic field lines would direct in the West direction at the lower wire.

To have the magnetic field lines in the upward direction concerning the Earth’s gravitational field and the right-hand rule, the current in the lower wire must be towards the North direction

Conclusion:

Thus, the direction of the current in the lower wire would be in the North direction.

(b)

To determine

To identify: Whether the upper wire can be held in stable equilibrium due to the magnetic force of the lower wire.

Answer to Problem 26Q

Yes, the upper wire will maintain its stable equilibrium.

Explanation of Solution

Introduction:

When a force is applied to any object, it tends to make equilibrium with the object and tries to maintain its position even if the variable force is applied to it.

Yes, the upper wire will be in a stable equilibrium position. If the upper wire tends to fall towards the lower wire then the magnetic force in between intends to maintain its position by pulling it apart.

Similarly, if the upper wire tends to move away from the lower wire then the force of gravity will be equally applied on it until it makes a constant position and distance with respect to the lower wire. This way, the upper wire will make a stable equilibrium position due to the magnetic force of the lower wire.

Conclusion:

Yes, the upper wire will be in a stable equilibrium position due to the magnetic field of the lower wire.