P4.2 Flashcards

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1
Q

Explain how a commutator keeps the coil spinning

A

Every half turn, each ring is connected to a different end of the power supply. The direction of the current changes and as a result the direction of the force changes. This ensures that the coil rotates in the same direction.

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2
Q

what is magnetic flux density measured in?

A

Tesla

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3
Q

equation for force

A

force = magnetic flux density x current x length

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4
Q

what happens to the current during the coils turn?

A

current changes direction every half turn

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5
Q

what happens to the forces on the coil during the turn?

A

forces on either side change direction every half turn

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6
Q

commutator

A

copper ring spilt into two parts

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7
Q

why at one point in the turn is there no forces acting on the coil?

A

the circuit is broken

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8
Q

why does the coil not stop when the circuit is broken?

A

because of the momentum

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9
Q

what happens when you put a wire carrying a current in another magnetic field?

A

the two fields add together

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10
Q

what is the motor effect?

A

a force will move the wire away from the strong part of the field and go towards the weak part of the field, this movement is called the motor effect

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11
Q

what is flemmings left hand rule?

A

F-force
B-magnetic field
I-current

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