Why like poles repel and opposite poles attract.
When a N and N pole are put side to side, they repel because the fields are going in opposite direction so they are wanting to move away from each other. When you put a N and S pole together, they attract because the fields are going in the same direction and are trying to become one magnetized object.
What causes magnetic fields?
Moving charges
What causes the Northern Lights?
Cosmic rays feel the force of earth's magnetic field and pulls the rays toward the magnetic poles of earth and because they are so concentrated on these two areas, you can see the force which is the lights.
How a magnet is weakened
When its domains are jostled by heat and collision
How a compass works
There is a magnet in the compass and its domains line up with those of the earth's magnetic field so the arrow points to the direction of the poles.
How does a laptop charger work?
The charger is AC. It puts energy into a secondary cell by forcing an electric current through it.
How Ferromagnetic materials are magnetized
The domains are aligned
Domain
A group of atoms whose electrons are spinning in the same direction.
Cosmic Rays
Cosmic rays are concentrated on the poles as a result of the earth's magnetic field
How a magnet picks up a paper clip.
1- domains in a paper clip are random. (domain: a cluster of atoms whose electrons are spinning in the same direction).
2- The magnetic has a magnetic field
3- When the magnet is close to the paper clip, the domains of the paper clip align to match the magnetic field of the magnet.
4- The paper clip now has a N and S pole and the N pole is attracted to the S pole of the magnet so they stick together.
Moving charges
A moving charge feels a force in a magnetic field.
Why do cosmic rays enter at the poles and not at the equator?
The moving charges feel a force from the magnetic field of the earth. this force causes them to spiral around the field lines and follow them into the poles.
How does a credit card machine work?
1- Magnetic strip
2- Code on strip
3- Reader has coils of wire that induce the voltage and current
4- Computer interprets electrical signals and converts them back to the code that's in the magnetic strip
Why do transformers not work with DC?
In order for a transformer to work, there needs to ne an alternating current so that the magnetic fields change. With DC there is only a direct current and the magnetic field would not alternate.
Transformer equations
pV/pT = sV/sT
Power (primary) = Power (secondary)
VI (primary) = VI (secondary)
No comments:
Post a Comment