Magnetic Effects of Electric Current


   
 
Electromagnetic Induction

  • Michael Faraday the English scientist was the first person to prove that a magnet can create a current

  • To test this he moved a magnet towards and away from the coil of wire connected to a galvanometer

  • He observed that there was a deflection in the galvanometer indicating that a current is induced in it

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  • The current obtained due to the relative motion between the coil and the magnet is called induced current

  • The phenomenon by which an emf or current is induced in a conductor due to change in the magnetic field near the conductor is known as electromagnetic induction

  • Faraday arrived at a few conclusions by moving a bar magnet in and out of the coil of wire

  • Some of the experiments performed by Faraday and his observations are tabulated here. Go through them

Experiment Observation
image Deflection in the galvanometer indicates that the current is induced in the coil due to the relative motion between the magnet and the coil.
image The deflection in the galvanometer is reversed when the same pole of the magnet is moved in the opposite direction.
image The galvanometer pointer comes back to the zero position indicating that the deflection in the galvanometer lasts as long as there is relative motion between the magnet and the coil.
image The deflection in the galvanometer is reversed when the opposite pole is moved in the same direction.
image The deflection in the galvanometer changes with the change in number of turns of the coil - more the number of turns in the coil greater the deflection. The magnetic field goes around each loop of wire in the coil, so if we increase the number of coils the change in magnetic field is more.
The magnet is moved faster in and out of the coil The deflection is more if the magnet is moved faster. That is, the rate at which the current is induced is more when the magnet is moved faster.

 
  
     
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