Electromagnetism Flashcards
What elements are able to be easily magnetized?
Iron, nickel, and colbalt
What are magnetic domains and what happens to them when a magnet is demagnetized?
Domains are areas in which the magnetic field of the atoms are lined up. When a magnet is demangetized, the domains go in all different directions
Magnetic Field Lines around a magnet
- The north and South poles exert a force
- The magnetic field always goes from north to south in coccentric circles
- the arrows point the direction that the field is in
- The closer the lines are, the stronger the field is
- The force will be strongest near the poles
Describe the behavior of magnetic poles
Unlike: Attract
Like: Repel
What happens to electrically charged particles in magnetic fields
They will be attracted to the electrical field of the magnet
- If the magnetic field is moving, then the electrically charged praticles will move
- The subatomic particles are always in motion
When an electric current flows through a conductor, it will create a magnetic field in what direction?
Using your right-hand:
Curl your fingers into a half-circle around the wire, they point in the direction of the magnetic field, B
Point your thumb in the direction of the conventional current.
How is an electromagnet built
An electromagnet is built when a coil, is wrapped around a magnetic bar of iron, nickel, of colbalt. A current must run through it. It is not a permanent magnet
What is the difference between an electromagnet and a permanent magnet
An electromanget’s properties go away once the current is taken away
A permanent magnet retains it s properties throughout whatever
Explain how an electric motor works..
- The electric motor consists of 4 electromagnets, a power source, a brush, and a commutator
- The commutator is responsible for switching the direction of the current, everytime the electromagnet changes direction
- The brushes are responsible for connecting the wires, the commutator
- When you turn on the power source, the current will run through two stationary electromagnets, that are connected by wires and the brushes to the commutator and two movable electromagnets
- When the current runs through, the coils on the electromagnet will all have the same charge . This being said, the electromagnet 1 is attracted to stationary electromagnet 4 because opposite poles attract. Then, you have to make sure that the brushes switch to opposite plates of the commutator
- Doing this will change the current so that the magnetic direction changes, and the the movable magnet’s poles change
- Lastly, because the movable magnets poles have changed, the movable magnet is attracted to the nonmovable magnet 2, and it keeps going like this
- The interia then carries it past, and the process starts again.
- The design results in continuous motion because, the magnets are always being either attracted or repelled
Explain How an Electric Generator Works
The electric generator uses Alternating Current
- The wire has to experience a changing magnetic field
- You take any motion, perhaps a fan. The wire will move and then create a changing magnetic field.
- For half a rotation, it produces current and then is taken out again. So, this alternating current.
4 This will work when a wire is through a magnet, or next to a magnet
What are transformers?
Transformers are devices that increase or decrease the voltage of alternating current.
Take a picture of a primary wire circuit, connected to a closed iron loop and nother wire.
- Primary wire is attatched to a source of alternating current. The other wire is attatched to an appliance
- When there is a current in the primary wire, it creates a changing magnetic field that magetizes the iron core. The changing magnetic field then induces a current into the second coil.
What are step up and step down transformers?
Because the amount of coil determines how strong and how many turns coil has, the more turns that it has, the more voltage that it will have. In step up: The 2nd coil will have more. In step down, the current will decrease
