When a conductor is exposed to a changing magnetic field, an electric current is induced in the conductor. This phenomenon, known as induced current, is a fundamental principle of magnetic induction.
To better comprehend induced current, we need to understand two important concepts: Lenz's Law and the relationship between current and magnetic field strength.
Lenz's Law states that the direction of the induced current in a conductor will always be such that it opposes the change that produced it. In other words, the induced current creates a magnetic field that counteracts the change in the original magnetic field.
For instance, if a magnet is moved towards a loop of wire, the changing magnetic field will induce a current in the wire. As per Lenz's Law, the induced current will create a magnetic field that opposes the motion of the magnet, resulting in a force of attraction between the magnet and the wire.
The magnitude of the induced current depends not only on the rate at which the magnetic field changes but also on the resistance of the conductor. According to Faraday's Law of Electromagnetic Induction, the induced electromotive force (EMF) is directly proportional to the rate of change of magnetic flux through a loop of wire.
A simple example to illustrate this is the movement of a bar magnet inside a coil of wire. When the magnet is rapidly moved in and out of the coil, the induced current is stronger due to the higher rate of change in magnetic field. Conversely, when the magnet is moved slowly or held stationary, the induced current is weaker since the rate of change is lower.
In summary, understanding induced current involves grasping the concept of Lenz's Law, which establishes the direction of the induced current, and recognizing the relationship between the current and the rate of change of magnetic field strength.