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## Physics library

### Course: Physics library>Unit 18

Lesson 7: Electric motor

# Spinning compass

By pulsing the connection to the battery we can cause a compass to spin. How is this working? Created by Brit Cruise.

## Want to join the conversation?

• Is there some benefit to the salt to the reaction and does it need it be used for this to work?
• what is this trying to show me
• This simple demo is the basis for the electric motor....Can you think of why this is? Is it possible to make something to spin without using your hands?
• so does the polls have anything to do with the compass here?
• since nickels and pennies are different types of metals(i'm pretty sure), how does it make the compass spin?
• all bodies have a natural magnetic field. the coils multiply/intensify this magnetic field when the electric current flows through them.
• could you replace the water with ice? what would happen?
(1 vote)
• I don't think that would work. The ions need to move around freely in the water.
(1 vote)
• Can we replace the salt water solution with a on/off switch or push button? I want to know what the significance of salt water is in this demonstration.
(1 vote)
• how much water did you use
(1 vote)
• would it still work without saltwater?
just curious...
(1 vote)
• It has to have an electrolyte solution to work, so Salt Water is good. Maybe Gatorade would also?
(1 vote)
• how come the compass moves faster ?
(1 vote)
• The more frequently he puts it in, the faster the compass needle will spin.
(1 vote)
• I get it now the salt water must be conducting a magnetic field
(1 vote)

Salt water.