Inducing a current using a magnet. Image credit

Inducing a current using a magnet. Image credit

ZIMSEC O Level Combined Science Notes: Introduction:Motors and generators

  • Electromagnetic induction- is the production of a voltage across an wires (electrical conductor )due to its dynamic interaction with a magnetic field.
  • If a magnet is inserted into a coil of wire connected to an electrical meter
  • A current is induced(created) in the coil
  • The electrical meter is known as a galvanometer
  • A galvanometer is an instrument for detecting and measuring small electric currents
  • When the magnet is pulled out of the coil
  • A current is induced again but in the opposite direction
  • This is shown on the galvanometer with the needle moving in the opposite direction
  • When compared to the direction it takes when the magnet is inserted
  • Induction happens because of the lines of force around a magnet
  • These lines “cut” the wires of the coil
  • The greater the rate of cutting the lines of magnetic force by the coil
  • The greater the current that is produced
  • The size of the current induced(produced/created) thus depends on:
  • The rate at which the magnet moves in the coil
  • The faster the coil moves the greater the current and vice versa
  • The current also depends on the strength of the magnet
  • The stronger the magnet the greater the current
  • The number of turns in the coil
  • The more turns there are the greater the current
  • If the magnet remains stationary in the coil no current is created
  • The current is only created when the magnet is inserted and pulled out of the coil
  • For current to be generated there has to be constant movement (flux) between the coil and the magnet(s)
  • In real world generators it is the coil that is moved inside a stationary movement
  • The coil is attached to turbines which are moved by water, wind, steam, fossil fuel motors etc
  • Generators can either produce Alternating current or Direct current
  • Alternating current constantly changes direction as the coil moves
  • Direct current only flows in one direction
  • Cells and batteries produce direct current

To access more topics go to the Combined Science Notes page.

Quick NetOne, Telecel, Africom, And Econet Airtime Recharge

If anything goes wrong, chat with us using the chat feature at the bottom right of this screen