MAGNETISM 2 H.P

• Copper wire is wound around a casing and spun around on a rotor.

• Strong magnets surround the coils as the coils spin.

• An electric field builds and electrons start to flow in a current.

• The electrical current can be sent through conductive wires to other locations.

Multiple Choice

A generator is basically....

• coils of wire turning inside a magnetic field.

• magnets circling a bigger magnet.

• coils of wires that have embedded magnets inside.

The strength of magnetic force

• The force of pull is called magnetic force

• A bar magnet’s magnetism is strongest at the ends. The ends of the magnet are called its poles

Open Ended

describe this image

we can conclude that

• Like poles repel

• Unlike/Opposite poles attract

Magnetic Induction

Magnetic induction

• by using a magnet the paperclips can become temporarily magnetized.

•  The steel in a paper clip can be easily magnetized but will lose this magnetism quickly.

• Materials that can be temporarily magnetized, but then quickly lose the magnetism are known as temporary magnets

Multiple Choice

Using the right hand grip rule, A represents the direction of the

• north pole

• current

Multiple Choice

Using the right hand rule, B represents the direction of the

• north pole

• current

Multiple Choice

Using the right hand thumb rule, if the current is going up on the front side of the coil then what side of the electromagnet is north?

• Up

• Down

• Left

• Right

Multiple Choice

In un-magnetized materials the domains are __________ aligned.

• super

• slightly

• randomly

• always

Multiple Choice

What kind of magnet can be turned on and off?

• refridgerator magnet

• electromagnet

• magnetite

• iron

Multiple Choice

Which direction is the North Pole of this electromagnet?

• Right
• Left
• Up
• Down

Multiple Choice

What is the device seen here?

• generator

• electric motor

• electromagnet

• magnet

Multiple Choice

Which of the following ways can cause a magnet to lose magnetic strength?

• Stroking it many times

• Coiling more turns around the magnet 

• Heating it over a fire

• adding more batteries to a magnet

Multiple Choice

• A

• B

• C

• D

Multiple Choice

• A

• B

• C

• D

Multiple Choice

Magnetic poles that are unlike

• attract each other.

• repel each other.

• do not interact.

• point in the same direction.

Multiple Choice

Why does a compass needle point north?

• It is repelled by the Earth's magnetic field located near the equator

• Because north is up

• It is attracted to the Earth's magnetic north pole

• It is attracted to the Earth's magnetic south pole

Multiple Choice

When would an electromagnet stop working?

• When the electric current is interrupted

• When it gets sunlight

• When it cools below 45 degrees

• After 24 hours

• All moving charges produce magnetic fields.

  • around a current carrying wire, magnetic field lines form circles (like the image to the left and above).

    • the direction of the magnetic field changes when the direction of the current changes.

    • the strength of the field can be increased by increasing the current.

      • as you mover farther away from the wire the field's strength decreases.

Hans was correct.

Hans Christian Oersted​

• year 1820

  • accidentally found that electricity and magnetism were related

    • observed how an electric current affected the direction of a compass needle

    • hypothesized that the current produced a magnetic field around the wire and that the direction of the field depends on the direction of the current

Multiple Choice

At which point is the strength of the magnetic field STRONGER around the wire?

• Point A

• Point B

• occurs when moving electric charges are surrounded by magnetic fields causing an electromagnetic force between the electric charge and magnets

Electromagnetism

the attractive or repulsive force that occurs between electric charges and magnets

• those interactions are called electromagnetism​

Electromagnetic Forces

these are temporary magnets created when there's a current in a wire coil

• the coil is normally wrapped around an iron core​ (such as an iron nail)

  • the coils magnetic field temporarily magnetizes the iron core​

Electromagnets

Electromagnet Strength

We can increase the strength of the electromagnet by:​

• increasing the number or coils (these are the loops or turns) around the iron core​

• increasing the current ​

​more coils = stronger magnet

Multiple Choice

Which screw would create the strongest electromagnet when a current is allowed to run through it?

• the screw with 50 coils

• the screw with 100 coils

• the screw with 150 coils

• the screw with 200 coils

electromagnets can rotate, converting electrical energy to mechanical energy

• speakers

  • the loudspeaker is an electromagnet connected to a flexible speaker cone​

• galvanometer

  • uses an electromagnet to measure electric current​

Uses for Electromagnets