1. Magnets and Magnetic Fields

2. What do you know about magnetism?
Crane Video
Electricity and magnetism are related!

3. Magnetism Readings
Modeling  independent work  compare notes

4. Magnetism Readings …Partner closer to the door
Turn and talk
…Partner closer to the door
What is a magnetic field?
…Partner farther from the door
What causes a magnetic field?

5. Magnetism Readings …Partner closer to the door
Turn and talk
…Partner closer to the door
What is a magnetic field?
A magnetic field is an area around a moving charge that exerts a force on other moving charges / other magnetized objects.
…Partner farther from the door
What causes a magnetic field?
Magnetic fields are creating by moving charges / current.

6. Magnetism Readings
Turn and talk
Compare and contrast electric fields and magnetic fields.

7. Magnetism Readings
Turn and talk
Compare and contrast electric fields and magnetic fields.
Electric fields are areas around stationary charges that can exert a force on other charges. Magnetic fields are areas around moving charges that can exert a force on other moving charges / magnetized objects.

8. Types of Magnets
Magnetic fields are created by moving electric charges … where are the charges??

9. Types of Magnets
Magnetic fields are created by moving electric charges … where are the charges??
Electromagnets
Magnetic field created by electric current
Can be turned on/off
Examples: junk yard cranes, components of motors, transformers, generators, speakers, etc.

10. Types of Magnets Permanent Magnets
The charges are the spinning electrons of the atoms!
All objects have spinning electrons, and each spinning electron has a mini-magnetic field around it
Usually, each mini-magnetic field points in a random direction
In a permanent magnet the mini-magnetic fields are aligned
non-magnet magnet

11. Types of Magnets Permanent Magnets
The charges are the spinning electrons of the atoms!
Examples:
Fridge magnets
A compass needle
The Earth!

12. Types of Magnets Turn & Talk Partner with longer last name…
Compare and contrast permanent magnets and electromagnets
Partner with shorter last name …
Identify an example of a permanent magnet and an electromagnet

13. Magnets are Cool! North (+) Pole and South (-) Pole Opposite Attract
Likes Repel N S S N N S N S

14. We can NEVER pull apart magnetic dipole
We can NEVER pull apart magnetic dipole. When we cut magnet in two we end up with two smaller dipoles. If we keep on cutting, more magnets will be produced, EACH with north and south pole.
Let’s Break A Magnet! N S
Magnetic monopoles have never been detected.

15. We can NEVER pull apart magnetic dipole
We can NEVER pull apart magnetic dipole. When we cut magnet in two we end up with two smaller dipoles. If we keep on cutting, more magnets will be produced, EACH with north and south pole. N S
Let’s Break A Magnet!
Magnetic monopoles have never been detected.
Just for fun …
Ever wonder why fridge magnets don’t seem to have poles … they do!

16. Earth’s A Magnet!
The poles received their names because of the behavior of a magnet in the presence of the Earth’s magnetic field. The pole of a magnetic needle that points to the north of the Earth is called north pole. So, magnetic pole which is in the geographic north is magnetically south pole.
Don’t freak out:
Earth's magnetic field has flipped many times over the last billion years. N S N S

17. The Magnetic Field 𝑩
A magnetic field is said to exist at a point if a compass
needle placed there experiences a force.
The direction of the magnetic field at any location is the direction in which the north pole of the compass needle points at that location.

18. Field Lines of Bar Magnet
Magnetic field lines don’t start or stop.
There are no magnetic charges (monopoles)
But don’t be confused if you see pictures on the right
(technically wrong, but commonly drawn)

19. Magnetic Field Lines
Arrows give direction to which a north pole will orient
Density gives strength
Looks like dipole! + -

20. Question
Which diagram shows the correct field lines of a bar magnet? (1) (2) (3)
Field lines should always point south
Field lines do NOT stop abruptly

21. Magnetic Field Lines activity
Place a magnet on a sheet of notebook paper and trace its outline.
Move a compass around the magnet, and sketch the field lines (where the north needle points)

22. Mini Posters
Include definition, picture, and where appropriate, variable and units and releavant equations.
electric field
magnetic field
charge
current
permanent magnet
electromagnet
resistance
potential
potential energy
power
work
force
Watch me!