1. Which way is the force acting?1. S

2. Which way is the force acting?2. S N

3. Which way is the force acting?3. S

4. More about induced current

5. 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

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

8. 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)

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

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

11. 2.
Try yourself N
Motion
Force
Magnetic field S
Induced Current

12. 3.
Try yourself S N
Motion
Force
Magnetic field
Induced Current

13. 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

14. 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.

15. 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

16. 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

17. Demo

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

19. Try Questions
Q Page 219

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

21. Next lesson - Transformers