Which way is the force acting? 1. S

Which way is the force acting? 2. S N

Which way is the force acting? 3. S

More about induced current

Learning Objectives A – To use both Fleming’s left and right hand rules M - to gain an understanding of how current is induced in coil of wire using a magnet S – to explain the difference between an A.C. and D.C. generator

Inducing Current Direction Lenz’s Law – an induced current always flows in the direction that oppose the change which it produced

Faraday’s Right hand rule To find out the direction of induced current from motion you must use faraday’s right hand rule (not left)

What direction does the current travel? Motion Motion Magnetic field Induced Current

Try yourself 1. N Motion Force Magnetic field S Induced Current

2. Try yourself N Motion Force Magnetic field S Induced Current

3. Try yourself S N Motion Force Magnetic field Induced Current

Left hand or right? To find out the force from the current its Left hand To find out the current from the motion its Right hand Motion Force Magnetic field Induced Current

Eddy Currents Eddy currents can be used to slow down a magnet with a non-magnetic metal A metal that is non-magnetic but conducts a current will generate Eddy Currents when it moves near a magnet. These currents oppose the motion of the metal and cause it to slow down.

Watch the video and answer these questions What type of current is used to levitate the plate? What type of metal is the plate made from? Is it magnetic? Do the two magnetic fields on faraday’s ring attract or repel each other? How large is the current being passed through the wires? What type of currents do you think are being generated in the metal plate (think of the material the plate is made from) What type of energy is a by-product these currents? Video

A.C. Generators Most of our electricity comes from electric generators. Simply put it is a coil of wire spun inside a magnet and an A.C current is produced

Demo

D.C. Generators The easiest way to make an A.C. generator D.C. is to add a commutator. How does a commutator work?

Try Questions Q 1 + 2 Page 219

EMF or Voltage “an electromotive force or potential difference expressed in volts” How much force the currents moves by…

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