What would happen if one were to move a bar magnet in and out of a coil of copper wire? A. The electric current would disappear. B. The magnet would not explode. C. The electric current would flow through the wire. D. It would not produce a gravitational field.
The Correct Answer and Explanation is:
Correct Answer: C. The electric current would flow through the wire.
Explanation:
When a bar magnet is moved in and out of a coil of copper wire, it results in the generation of an electric current in the wire. This phenomenon is known as electromagnetic induction, and it was first discovered by Michael Faraday. According to Faraday’s Law of Electromagnetic Induction, a changing magnetic field within a closed loop of wire induces an electromotive force (EMF), which in turn causes an electric current to flow.
As the magnet moves into the coil, the magnetic field through the coil increases. This change in magnetic flux induces a current in a direction that opposes the increase, according to Lenz’s Law. When the magnet is pulled out of the coil, the magnetic field through the coil decreases, and the induced current then flows in the opposite direction to oppose the decrease.
The key factor is the motion of the magnet relative to the coil. A stationary magnet does not cause a change in magnetic flux, and thus does not induce current. But moving the magnet (either into or out of the coil) changes the magnetic field in the coil over time. The faster the magnet moves, the greater the rate of change of magnetic flux, and therefore, the greater the induced current.
This principle forms the basis of electrical generators, where mechanical energy is converted into electrical energy by rotating coils within magnetic fields. The copper wire does not need to be connected to a battery; the motion of the magnet alone is sufficient to induce the current, demonstrating that a magnetic field in motion relative to a conductor can generate electricity.
Therefore, the correct answer is C. The electric current would flow through the wire.
