1. True or False
Field lines show the direction of travel for a negatively charged object.
Hitting a magnet will a hammer with magnetise it
Magnetic field lines enter at the South Pole
Earth’s North magnetic pole is found in Canada
Two like poles will repel one another
A piece of unmagnetised iron will always repel an existing magnet

2. True or False
Field lines show the direction of travel for a negatively charged object.
Hitting a magnet will a hammer with magnetise it
Magnetic field lines enter at the South Pole
Earth’s North magnetic pole is found in Canada
Two like poles will repel one another
A piece of unmagnetised iron will always repel an existing magnet

3. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.

4. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
If an electric current is passed through a wire it produces a weak magnetic field.

5. . Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Field entering the page . .
Field exiting he page

6. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
A way to remember the direction of the field is the right hand grip rule:

7. The magnetic field around a current-carrying wire is very weak.
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
The magnetic field around a current-carrying wire is very weak.
So weak that it is practically useless.
But… the idea of a magnetic field which can be switched on and off at will sounds very appealing!

8. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
In order to make a magnet which might be strong enough to be of use we can wrap current carrying wires around a metal core.
Iron is best but any core will work providing the wire can be wrapped around.

9. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
We can use the right hand grip rule for coils of wire too, to help identify the N and S poles.

10. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
We can use the right hand grip rule for coils of wire too, to help identify the N and S poles.

11. Draw the pattern of field lines around each of the examples…b) d) . . e)

12. Score yourself… a) Current entering page. 1. Circles. 2
Score yourself… a) Current entering page 1. Circles 2. Clockwise b) Earth 1. Just like a bar magnet 2. Field lines entering South Pole *bonus mark if you have the South Pole in the Northern Hemisphere. c) Solenoid 1. Just like a bar magnet 2. North at left end. d) Current exiting the page 1. Circles 2. Anticlockwise e) Three bar magnets 1. Field lines out of North and into South 2. Direct field lines between opposite poles

13. How would you investigate the effect of current?
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Experimenting with Electromagnets
By using the mass of paper clips which can be picked up as a proxy for the magnitude of the magnetic field strength, find out how the number of coils affects the strength of the magnetic field around an electromagnet.
How will you make your results reliable?
You are going to need to draw a graph to interpret your results. How many data points do you need?
Finished?
How would you investigate the effect of current?

14. Experimenting with Electromagnets
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Experimenting with Electromagnets
We already know the graph will show that as number of coils increases so too will the mass of paper clips but is the relationship fully linear?
Which of these graph shapes do you think will be correct and why?
Mass of paper clips / g
Number of coils

15. Investigating the effect of current
Current (A)
Mass (kg)
0.4
0.5
1.0
1.5
0.6
2.0
0.7
3.0
Plot a graph of the results… is the relationship proportional?
How could you use the data (without a graph) to test if the relationship was proportional?

16. If we increase the current we increase the strength of the field.
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
The magnetic field around a coil of wire (solenoid / electromagnet) is very similar to that produced by a bar magnet.
If we increase the current we increase the strength of the field.
If we increase the number of coils we increase the strength of the magnet.
If we use a metal core (iron) we increase the strength of the magnet.

17. Uses of electromagnets?
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Uses of electromagnets?

18. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Scrap Yards
A large electromagnet is used in a scrap yard to pick up and move heavy pieces of scrap metal.
Which metals would the electromagnet attract?
What advantages does an electromagnet have over a permanent magnet?

19. Research Electric Bell and Relay switch
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Research
Electric Bell and Relay switch
Stick in and label the diagrams of the relay switch and electric bell.
Use p 334 – 335 of your text book to answer two 6 mark questions;
“Describe and explain the operation of the electric bell (6) and relay switch (6)”

20. Using electromagnets – Door Bells
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Using electromagnets – Door Bells
The circuit for a door bell includes an electromagnet.

21. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Relay Switch
Lifts, cars and other large electrical machines use very high electrical currents
A relay, which includes an electromagnet, is used to allow a small current in one circuit to control a large current in another circuit.

22. Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Relay and Bell
Using a red pen / pencil draw arrows to explain how the internal movements of the low current circuit control the high current circuit in a relay.
Explain why a relay switch might be used in a kitchen appliance such as a washing machine.
Using a red pen / pencil draw arrows to explain how the internal parts of a door bell work in order to produce the noise we hear.
Explain why a permanent magnet would not be suitable to this task.

23. 3 ways of making an electromagnet stronger 2 uses of electromagnets
Specification Aims By the end of this lesson you should be able to…
Distinguish between the design and use of permanent magnets and electromagnets.
Describe the pattern of magnetic fields around straight wires and solenoids (electromagnets).
Use the right hand grip rule to explain how the direction of the field can be changed.
Reminding yourself…
3 ways of making an electromagnet stronger
2 uses of electromagnets
1 rule for understanding the shape of the magnetic field around a solenoid.