The Motor Effect and Electric Motors

Why might a current-carrying wire be placed in a magnetic field?

• To increase the current from the interaction of magnetic fields

• To increase the voltage from the interaction of magnetic fields

• To produce a force from the interaction of magnetic fields

What does the thumb indicate in flemings left hand rule?

• Force

• voltage

• Current

• Magnetic field direction

What direction is the force/motion in the following diagram?

• Perpendicular to the magnets

• Downwards

• Parallel and through the magnets

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What angle must there be between magnetic field lines and a conductor in order for the maximum force to be exerted?

• 180

• 45

• 90

• 270

Name one factor that does not affect the size of a force in on a current-carrying conductor placed in a magnetic field?

• Gravity

• Magnetic flux density/size of magnetic field

• Size of the current

• Length of the conductor

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Name the effect that causes a coil of current-carrying wire in an electric motor to move.

• The electromagnetism effect

• The magnetic effect

• The motor effect

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Which rule can be used to work out which way a coil of wire rotates in a motor?

• Fleming's left-hand rule

• Fleming's right-hand rule

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Give two ways you can reverse the direction of a basic dc motor?

• Reverse the current

• Keep the current the same

• Reverse the magnetic field

• Keep the magnetic field the same

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How does a split ring commutator work?

• Swaps the contact evert full turn, so that the left-hand and right-hand arms of the coil always experience a force in the same direction.

• Swaps the contact evert half turn, so that the left-hand and right-hand arms of the coil do not experience a force in the same direction.

• Swaps the contact every half turn, so that the left-hand and right-hand arms of the coil always experience a force in the same direction.

What does the second finger represent in Flemming's left hand rule?

• force

• current

• field

• voltage