1. Gravitational, Magnetic and Electrical Fields

2. Gravitational Fields - Review
Law of Gravity–any two masses exert an attractive force on each other
This attractive force depends 2 things
Mass of the objects
Distance between the objects
As the mass of the objects increases, the force of gravity between them increases
As the distance between the two objects increases, the force of gravity between them decreases

3. Gravitational Fields-Review

4. Magnetism
magnetism – refers to the properties and interactions of magnets

5. Magnetism
Factors that Affect Magnetic Force
as objects move closer together, the magnetic force between them increases
magnets have two ends which are called magnetic poles
unlike poles attract
like poles repel

6. Magnetic Fields
Factors that Affect Magnetic Force
a magnet is surrounded by a magnetic field that exerts a magnetic force.
the magnetic field is strongest close to the magnet and weakest far away from the magnet
can be represented by lines of force around the magnet

7. Magnetic Fields
Factors that Affect Magnetic Force
a magnet is surrounded by a magnetic field that exerts a magnetic force.

8. Magnetism all magnets have a north pole and a south pole
Magnetic Poles
all magnets have a north pole and a south pole

9. Magnetism all magnets have a north pole and a south pole
Magnetic Poles
all magnets have a north pole and a south pole
North pole – South pole : attract each other
North pole – North pole : repel each other
South pole – South pole : repel each other
magnetic field lines always connect the north and south poles of a magnet.

10. Magnetism
A Compass Needle
a compass contains a needle that has a small bar magnet on it

11. Magnetism
A Compass Needle
a compass contains a needle that has a small bar magnet on it
the needle aligns itself with the magnetic field line so that the north pole of the magnet aligns itself with the south pole of a bar magnet
a compass also aligns with Earth’s magnetic field normally and points north

12. Magnetism
Earth’s Magnetic Poles
the south magnetic pole is near the north geographic pole and the north magnetic pole is near the south geographic pole.
so the north pole of a compass is being attracted by the south magnetic pole

13. Magnetism Earth’s Magnetic Poles
so the north pole of a compass is being attracted by the south magnetic pole

14. Magnetism
Magnetic domains – groups of atoms having aligned magnetic poles
atoms surrounding a magnet will align themselves with overall north and south poles to make the magnetic material a magnet

15. Magnetism
Magnetic domains – groups of atoms having aligned magnetic poles
only temporary magnetism will exist until the external magnet is removed
This only occurs to magnetic materials such as iron, cobalt and nickel
Permanent magnets are formed by placing a piece of magnetic material in a strong magnetic field to cause a large number of the magnetic domains in the field to line up.

16. Magnetism Permanent magnets cont.
Once turned into a permanent magnet, it can retain it’s magnetic properties for a long time.
Although, they too can lose their magnetic properties if they’re heated or dropped.

17. Magnetism

18. to cancel each other out.
Magnetic Domains
Iron nails have a HUGE amount of these domains, yet they don’t behave as magnets, why do you think that is?
So why then does a nail “stick” to a magnet?
Because all these domains are arranged randomly and point in different directions, this causes them
to cancel each other out.
The atoms in the nail will align themselves to the magnetic field lines of the magnet. This will cause the nail’s domains to temporarily point in the same direction and no longer cancel out.

19. Magnetic Domains How does it become “de-magnetized”?
Once you take the magnet away, the domains are no longer aligned, and the nail’s domains go back to normal. Paper clips can also be turned into “temporary magnets”.

20. Electric Fields
Just as magnets are surrounded by magnetic fields, flowing electrons are surrounded by electric fields.

21. Coulomb’s Law
Coulomb’s Law states that the electrostatic force between two objects varies with charge and distance.
This is similar to the Law of Gravitation
distance and mass affect the force of gravity between two objects

22. General Facts to Aid us OPPOSITES ATTRACT!!
Positive + Positive = Repel
Positive + Negative = Attract
Negative + Negative = Repel

23. Predict:
Would 2 particles with the same charge (negative & negative or positive & positive) repel or attract?
Would 2 particles with different charges (positive and negative) repel or attract?

24. Predict
What do you think would happen to the force between two objects of different charge (positive and negative) that were pulled further apart?
What do you think would happen to the force between two objects of different charge (positive and negative) that were pulled closer together?
They would still be attracted towards each other due to opposite charges, but the greater distance will cause a weaker force between them.
They would still be attracted towards each other due to opposite charges, and the smaller distance will cause a greater force between them

25. Predict
What will happen to two particles with the same charge (negative and negative) that are pulled farther apart?
What will happen to two particles with same charges (negative and negative) that are pulled closer together?
They would repell each other due to similar charges, & the greater distance will cause even less force between them
They would repell each other due to similar charges, but the smaller distance will cause an even bigger repulsion force between them.