Question

Use the right-hand rules to show that the force between the two loops in Figure 22.49 is attractive if the currents are in the same direction and repulsive if they are in opposite directions. Is this consistent with like poles of the loops repelling and unlike poles of the loops attracting? Draw sketches to justify your answers.

Short answer

Same direction current causes attractive force, opposite direction causes repelling force.

Step-by-step solution

Definition of force and torque.

Force: Force is an external agent capable of changing the state of rest or motion of a particular body. It has a magnitude and a direction.

Torque: Torque is the measure of the force that can cause an object to rotate about an axis. Force is what causes an object to accelerate in linear kinematics.

Explanation

If we take one part of the loop, any part, and consider it as a very short straight wire, we can point our thumb in the direction of the current to find the direction of the magnetic field. We can do that for both of the loops. If we look at one part of the loop as a wire, and the current that is flowing through the part of the second loop as a charge in motion, we can use the right-hand rule to show that in case that velocity, which is also the direction of the current, is facing the same way for both loops is causing attractive force, and in case they are opposite direction, repelling force.

Therefore current in the same direction causes attractive forces and opposite direction current causes repelling forces.