Electricity 1: Magnetism

What is a magnet?

any material that attracts iron or ferrous materials

What is a magnetic field?

The assumed area around a magnet consisting of invisible lines of force from the north pole to the south pole of the magnet

What is the rule of magnetic attraction?

Like poles repel, and unlike poles attract

What is a permanent magnet?

a material that maintains it magnetic force over a long period of time

Do magnetic poles match the geographic poles on earth?

No, they do not match.

What is magnetic variation/declination?

The difference between the magnetic poles and the geographic poles .

What is residual magnetism?

When a material's molecules algin themselves with a nearby magnetic field, and then the material's molecules unalign themselves when not in the presence of a magnetic field.

What is permeability?

A material's ability to become magnetized

A material with high permeability...

is easy to magnetize.

A material with low permeability...

is hard to magnetize

How do lines of magnetic flux travel?

From north to south

What are the 5 properties of lines of Magnetic Flux?

1. closed and continuous

2. travels from north to south outside the magnet and south to north inside the magnet

3. concentrated at the poles

4. mutually repel each other

5. Never interest each other

What is a ferromagnetic material?

a material that is easily magnetized.

Ex. iron, nickel, cobalt

What is a paramagnetic material?

A material that can be magnetized, but not as easily.

Ex. platinum, titanium, and chromium

What is a diamagnetic material?

A material that CANNOT be magnetized

Ex. copper, brass, antimony

What is an electromagnet?

A device that uses an electrical current to create a magnetic field.

How does an electromagent increase its magnetic field?

By increasing the current flow

What are the two factors to determine the number of flux lines in an electromagnet?

1. The number of turns in the coil of wire

2. The amount of current flow in the wire

The strength of an electromagnet is...

proportional to its ampere turns

An air core magnet contains?

Non-magnetic core materials

An iron core magnet contains?

A core made of mild iron. This increase the number of flux lines therefore increasing the strength of the magnet.

What is reluctance?

Resistance to magnetism

What is saturation?

all molecules of a magnetic material line up

How to determine electromagnet polarity?

Using the left hand method.

What is demagnetization?

Molecules being disarranged in a non-magnetized material.

3 methods of demagnetization

1. placing the object in a field of a strong electromagnet in a AC line

2. striking the object

3. heating the object

Common magnetic devices?

Electromagnets, measuring instruments, solenoid, transformers, motors, and generators.