Electro-Magnetism

Magnetism is generated by moving

• protons.
• electrons.
• neutrons.
• elements.

An electromagnet's poles may be reversed by:

• decreasing the voltage of the coil
• increasing the number of coils
• changing the direction of current flow
• altering the material used to make the coils

The needle of a compass points towards the north because...

• the Earth's magnetic south pole is situated near the Geographic North Pole.
• there is a battery inside the compass.
• The Earth attracts the south pole of the needle.
• There is a mass of iron inside the compass.

If you cut a magnet in half, what happens to the poles?

• One half gets the North Pole, the other half gets the South Pole
• Both halves get only a North Pole
• Both halves get only a South Pole
• Both halves get a North pole and a South Pole

If you wrap more coils around an electromagnet, it will become...

• brighter
• stronger
• weaker
• invisible

2 ways to increase the magnetic force of an electro-magnet

• Increase the current flow, reduce the number of coils
• Increase the voltage, decrease the number of coils
• Increase the number of coils and the current flow
• Spread out the coils, replace iron core with rubber.

As the distance between two magnets increases (they get farther apart), the force between them:

• Increases
• Decreases
• Stays the Same

What is responsible for the Magnetic Field around Earth?

• The Earth's crust
• The Earth's molton iron core
• The Earth's mantel
• The Sun

If the North Pole of a permanent magnet is placed next to a compass as seen in the picture, which direction will the needle move?

• Clockwise
• Counter-clockwise
• It will not move
• Need more information

Which direction is the North Pole of this electromagnet?

• Right
• Left
• Up
• Down