Electromagnetic induction is this cool concept in physics that Michael Faraday stumbled upon back in the 1800s. So, imagine you’ve got a magnetic field—that invisible force around magnets. Now, take a metal conductor, like copper or aluminum, and throw it into this magnetic field. When there’s movement between the conductor and the magnetic field, or if the magnetic field changes, magic happens.
Now, let’s talk about magnetic flux. It’s like a measure of how many magnetic field lines cross a surface. You can calculate it using the strength of the magnetic field and the area the field lines are passing through, taking into account the angle.
A magnetic field is a region where a magnetic force is exerted on moving charged particles. It is represented by lines of flux that flow from the north pole to the south pole of a magnet.
The strength of a magnetic field is measured in units called Tesla (T).
A conductor is a material that allows the flow of electric current. Common conductors include metals like copper and aluminum.
When a conductor is placed within a magnetic field, it experiences a force if there is relative motion between the conductor and the magnetic field or if the magnetic field strength changes.
Magnetic flux () is a measure of the quantity of magnetic field lines passing through a surface perpendicular to those lines.
It depends on the strength of the magnetic field () and the area () through which the magnetic field lines pass: , where is the angle between the magnetic field lines and the surface.
Faraday's First Law of Electromagnetic Induction
The first law of electromagnetic induction states that the electromotive force (EMF) induced in a coil is directly proportional to the rate of change of magnetic flux through the coil.
is the induced EMF (measured in volts).
is the change in magnetic flux (measured in Weber, Wb).
is the change in time (measured in seconds)
Faraday's Second Law of Electromagnetic Induction
The second law of electromagnetic induction quantifies the induced EMF by providing a more detailed expression. It states that the magnitude of the induced EMF (e) is equal to the rate of change of magnetic flux (), taking into account the number of turns in the coil ( ).
is the number of turns in the coil.
This law builds upon the first law by incorporating the number of turns in the coil. The more turns a coil has, the greater the induced EMF. It emphasizes that the total induced EMF is the product of the rate of change of magnetic flux and the number of turns in the coil. Again, the negative sign signifies the direction of the induced current.
Lenz’s Law, a buddy to Faraday’s Law, says the direction of the induced current is going to be such that it fights against the change in magnetic flux. It’s like a law of nature to make sure we’re not creating an infinite energy loop.
Eddy currents are circulating currents induced in a conductor when it is exposed to a changing magnetic field. These currents circulate within the conductor in closed loops and can generate heat due to the resistance of the material. Eddy current phenomena are particularly significant in conductive materials, such as metals.
Type of Induction
Mutual induction occurs when the change in current in one coil induces an electromotive force (EMF) in an adjacent coil. This is the fundamental principle behind transformers, where two coils share magnetic flux.
It is measured in Henry (H). One Henry of mutual inductance means that a change in current of one ampere per second in one coil induces an EMF of one volt in the other coil.
Self-induction happens when a changing current in a coil induces an EMF in the same coil. This phenomenon is crucial in the operation of inductors, which are components used to store energy in magnetic fields.
It is measured in Henry (H). One Henry is the self-inductance of a coil when an EMF of one volt is induced by a change in current of one ampere per second.