# Difference between motor effect and electromagnetic induction?

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#1
In the context of GCSE exams, how should I decide whether a particular question is about the motor effect or about electromagnetic induction?
0
7 years ago
#2
(Original post by Wawasan)
In the context of GCSE exams, how should I decide whether a particular question is about the motor effect or about electromagnetic induction?
The motor effect causes a force to occur
EM induction causes a current to occur when a force is applied

Look at the question: is there a battery motor effect
if there are obvious force arrows induction

If they have actually drawn out a motor/generator then the only way to tell is by whether the question says a current is flowing or whether it says steam/whatever is pushing around the loop. Someone will have to back me up on this, but I think DC motors have split rings, while generators have slip rings.

Finally, its horrendously unlikely that this would be useful in an exam, but you could put in a really sensitive ammeter and work out whether the current flowing is AC/DC.
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7 years ago
#3
(Original post by lerjj)
Someone will have to back me up on this, but I think DC motors have split rings, while generators have slip rings..
Yep, pretty sure I've heard this as well. Motors require the polarity to be reversed every half turn, while generators simply require a constant connection.

(Original post by Wawasan)
In the context of GCSE exams, how should I decide whether a particular question is about the motor effect or about electromagnetic induction?
If you have a force (movement) and a conductor cutting through a magnet, it's induction.

If you have a current and a magnetic field, but no external movement, it's the motor effect.

Think about what you're missing out from the question, and use that to decide which one it is.

Posted from TSR Mobile
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7 years ago
#4
(Original post by Wawasan)
In the context of GCSE exams, how should I decide whether a particular question is about the motor effect or about electromagnetic induction?

The motor effect is the effect whereby a wire or coil with a current in and placed in a magnetic field experiences a force.

Electromagnetic induction (the generator or dynamo effect) is the effect whereby a wire or coil moving in a magnetic field generates an emf.
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#5
Ah, got it now. Thanks guys
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