Electromagnetic Induction

 
4.2  Electromagnetic Induction
 
  Electromagnetic induction  
 

The production of induced electric current without the use of any source of electricity by making relative motion between conductors or magnets.

This causes a magnetic flux change in the conductor.

Electromagnetic induction also causes kinetic energy changes to electrical energy.

It is produced in a straight wire or solenoid.

 
     
 

The induced current production is summarized as follows:

  1. Voltage is generated when a straight wire is moved across a magnetic field on a permanent magnet or a permanent magnet is moved in a solenoid.
  2. If the voltage is generated, then the induced current will also be generated.
  3. The existence of induced currents can be proven by the movement of the needle deflection on the galvanometer.
 

 In simple terms:

\(\text {Force + Magnetic field} = \text {Induced current} \)

The direction of the induced current flow can be determined by Fleming's right-hand rule.

 

The laws that are used in the concept of electromagnetic induction are Faraday's law and Lenz's law.

 
  Faraday's Law  
 

The magnitude of the electromotive force (e.m.f) is directly proportional to the rate of change in the magnetic flux.

The more and faster the magnetic field is “cut off,” the more current is generated.

 
     
 
  Lenz's Law  
  The resulting induction current is always flowing in the direction that opposes the change in magnetic flux that produces it.  
     
 
 

When the north pole of the magnet approaches the solenoid, the solenoid will reject the magnet.

To reject the north pole, the magnetic field on the solenoid becomes the north pole.

When the north pole of the magnet is away from the solenoid, the solenoid will turn to the south pole to retract the magnet.

As the poles change, the direction of the current also changes.