Electromagnetic Induction

• 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.