Unit 9 - Electricity & Magnetism (2)

Unit 9 - Electricity & Magnetism (2)

By S Harris

i know...

• how to relate electric current to magnetism.​

Learning Target

​

I can...

• determine the strength of an electromagnet by the number of coils used to create the magnet.​

​​Success Criteria

​

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

• 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.

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