Question

As an externally generated magnetic field through a certain conducting loop increases in magnitude; the field produced at points inside the loop by the current induced in the loop must be:

a) directed opposite to the applied field
b) perpendicular to the applied field
c) in the same direction as the applied field
d) increasing in magnitude
e) decreasing in magnitude

Answer 1

The magnetic field produced inside a conducting loop by the induced current must be directed opposite to the increasing externally applied magnetic field, in accordance with Lenz's Law and exemplified by using the right-hand rule for direction determination.

Step-by-step explanation:

When an externally generated magnetic field through a conducting loop increases in magnitude, it causes a change in magnetic flux. According to Lenz's Law, the induced current in the loop will create a magnetic field that opposes the change in flux. Therefore, the correct answer is that the magnetic field produced at points inside the loop by the current induced in the loop must be directed opposite to the applied field.

The induced current and its magnetic field act to maintain the status quo of the original magnetic flux through the loop. If a magnet's south pole, for example, approaches the loop, increasing the magnetic flux, the induced current will flow in a direction such that it creates a similar south pole that repels the approaching magnet—hence opposing the increase in magnetic flux.

Using the right-hand rule (RHR-2), when the thumb points away from the magnet, the fingers wrap in the direction of the induced current, which is clockwise when a south pole approaches (as viewed from the magnet) and counterclockwise when a north pole approaches.