Electric and Magnetic Forces in Generators

Motors and Generators

Motors: Electrical Energy Mechanical Energy

• Electrical energy is used to create a current in an armature (the coil)

• The armature is in a magnetic field and has its own magnetic field due to the current flowing through it

• The armature turns so that its magnetic field lines up with the magnetic field of the magnet

• A moving magnetic field causes a voltage to be created/induced

• If there is a complete circuit, this voltage will result in a current flowing

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Electromagnetic Induction

• N pole into the coil = positive voltage induced

• Magnet at rest in coil = no voltage induced (because magnetic field isn't changing!)

• Move magnet backwards out of coil = negative voltage induced

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Electromagnetic Induction

​Generators typically produce alternating current (AC)

1. Using a stronger/bigger magnet

2. ​Moving the magnetic field faster

3. More windings/loops in the coil

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Induced voltage can be increased by...

Generators: Mechanical Energy Electrical Energy

• Mechanical energy is used to turn a rotor attached to an armature (coil)

• The armature is in a magnetic field

• As the wire is turned, it experiences a changing magnetic field

• This results in a voltage and current

• Input: Electrical energy (battery)

• Output: Mechanical energy (coil turns)

• Motor parts: battery

Motors only

• ​Input: Mechanical energy (turn the coil)

• Output: Electrical energy (voltage and current)

• Motor parts: device to be powered

​​Generators only

Parts:

Magnet

Armature

Both

Multiple Choice

Generators are devices that convert _____ energy into _____ energy.

• chemical; mechanical

• mechanical; electrical

• electrical; mechanical

• potential; kinetic

Multiple Choice

What device is made of coils of wire with an electrical current passing through it in order to generate a magnetic field?  

• Electromagnet 

• Generator

• Electron Magnet 

• Motor

Multiple Choice

Electric motors are devices that convert _____ energy into  _____ energy.

• electrical; mechanical

• mechanical; electrical

• chemical; potential

• mechanical; kinetic

Multiple Choice

What two forces are required for generators and electric motors to work?

• magnetism and thermal

• electricity and thermal

• electricity and magnetism

• magnetism and radiant

Multiple Choice

The voltmeter is at 0 in this image. How would you manipulate the experiment to create electricity (measured in volts)?

• Flip the magnet around so the North pole is facing out
• Move the magnet back and forth
• Take the magnet out
• Add more coils around the paper cylinder

Multiple Choice

How could the experimenter increase the amount of electricity being induced by this experiment?

• Increase the number of coils

• Decrease the number of coils

• Flip the magnet around

• Nothing, the amount of electricity cannot be increased