1. Electricity and Magnetism
Electromagnetism

2. What is magnetism? How can you define magnetism? What is a “magnet”?
The phenomenon caused by magnets
What is a “magnet”?
An object which can attract other objects containing iron, cobalt or nickel
Types of magnets
Electromagnets
Permanent magnets

3. Magnet basics Two poles to each magnet As with electricity:
North and South
As with electricity:
Opposite poles attract
Like poles repel
This is due to how the magnetic field looks
Note
Breaking a magnet makes smaller magnets with a N and S pole

4. Breaking a magnet

5. A Magnetic Field

6. Electromagnetism Magnetism caused by electricity
In a coil (solenoid) or a wire
How are we to know how the magnetic field (MF) will look like?
Where can we find the North and South poles?
Right hand rule (RHR)
Wrap your hand around the wire or coil with your thumb pointing with the direction of current
Fingers illustrate the flow of the magnetic field

7. Right Hand Rule

8. Right Hand Rule

9. Right Hand Rule

10. Right Hand Rule

11. In a Solenoid or a Wire The magnetic field can be turned on or off
This is not true in a permanent magnet
The direction of the magnetic field can be reversed
Reversing the current reverses the field
The intensity of the magnetic field can be modified
A stronger current causes the magnetic field to increase

12. What is an electromagnet?
By taking an solenoid and inserting a ferromagnetic core and turning on the current
In this case, the magnetic field is coming from both the wire and the core.
The field strength can be altered
What can be modified to change the strength of the field?

13. Electromagnets

14. Electromagnets

15. Electromagnet

16. How to increase a MF in an electromagnet?
By increasing the number of turns in the solenoid
More turns = stronger field
Increasing the current
Stronger current, stronger magnetic field
Changing the core
A core with a lower magnetic remanence

17. Wire vs Magnet How do the magnetic fields differ? Magnet Wire
Flows from North to South around the magnet
Wire
Flows circularly around the magnet
There is no N or S