1. Electromagnetism
Motors and Generators

2. Summarise this in your book.
The Motor Effect
When a conductor carrying a current is placed in a magnetic field ( or vice versa) the magnet producing the field and the conductor exert a force on each other.
What does the direction of the force depend on?
Demonstrate the motor effect, reverse the current and the direction of the magnetic field separately. Then reverse both together and get them to predict no change.
Summarise this in your book.

3. Why?
HINT: Think about the magnetic fields involved N S N S

4. Summarise this in your book.
Which way?
We can work out the direction of this induced (made) force using Flemings left hand rule.
Your index finger in the direction of the magnetic field (North to South)
Your second finger in the direction of the current.
Your thumb will point where the force is acting.
Summarise this in your book.

5. Now try it for yourself. Which way do these move
Now try it for yourself. Which way do these move? Sketch two into your books and use FLHR to label up the direction of the force experienced.
Easier
Harder

6. Easier Harder Using a different colour, mark your answers.
Towards you, e.g.out of page
Towards you, e.g. out of page

7. What about size?
NB: it is only the current flowing at a right angle that counts.

8. Now try it. Each is worth 4 marks. - check these!
Grade 6/7
Grade 8/9
A 0.1 m wire is inside a 2.0  10–4 T magnetic field and the current flowing is 8 A what force is experienced?
If a 0.2m wire moves upwards with a force of 2.4 N when the current flowing is 1.2 A, what was the magnetic field?
What force is induced if a 0.25 m length of a wire carrying a 4 A current experiences a magnetic field of 1.5 x 10-3T?
A wire is inside a 0.32mT magnetic field and the current flowing is 1.5 A. If the force experienced is 0.02N find the length of wire.

9. The Electric Motor

10. Split-ring commutator
Reverses current each time coil passes vertical.

11. Boardworks GCSE Additional Science: Physics Motors and Generators
Teacher notes
This activity extends the idea of a simple current-carrying coil rotating in magnetic field from slide 8, and explains how a split-ring commutator enables a coil to continue rotating. Students could again be asked to interpret the movement of the coil using Fleming’s left-hand rule.

12. Boardworks GCSE Additional Science: Physics Motors and Generators
Teacher notes
This simulation takes the concepts from the previous slide to create an animated motor simulation. The current, forces and magnetic field can be toggled on and off, to aid visualization and understanding, and the speed and direction of rotation can be altered.

13. Examples of electromagnetic Induction
Generators
Examples of electromagnetic Induction

14. Cutting magnetic field lines
When the wire AB moves vertically, it cuts magnetic field lines – voltage induced
When the wire moves horizontally, no field lines cut – no voltage induced

15. a.c Generator
Demo generator hooked up to picoscope with ac and dc generations being seen clearly

16. How do AC generators work?
Boardworks GCSE Additional Science: Physics
Motors and Generators
How do AC generators work?
Teacher notes
This activity extends the idea of simple electromagnetic induction from slides 16 and 19, and explains how slip rings enable a generator to produce alternating current.

17. AC generator simulation
Boardworks GCSE Additional Science: Physics
Motors and Generators
AC generator simulation
Teacher notes
This simulation takes the concepts from the previous slide to create an animated generator simulation. The current, forces and magnetic field can be toggled on and off to aid visualization and understanding.

18. Cutting magnetic field lines (flux lines)

19. What about a DC Generator?
Try the video clip on this link to help you.