The circuit of the induction coil

AI Thread Summary
When the circuit with an AC source and an induction coil is turned off, an induced electromotive force (emf) occurs due to the changing magnetic field. The induced emf reaches its maximum when the current is zero, raising questions about its relationship with the source emf. Despite having equal magnitudes and opposite directions, they do not cancel each other out because a voltmeter cannot detect instantaneous voltage. An oscilloscope is recommended for a clearer view of the instantaneous voltage across the induction coil. According to Kirchhoff's rule, the sum of the voltages around the closed circuit remains zero at all times.
Aya Elsayed
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When we turn the circuit off . There will be an induced emf through the coil due to the changing magnetic field of the AC . Therefore V=-L . DI/Dt
So when the current is zero then the emf has a maximum value . And what about the emf of the source itself ? It's equal to the induced emf? If It has the same value and an opposite direction whey they don't cancel each other out ?
 
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Aya Elsayed said:
When we turn the circuit off.
What circuit? Can you be more specific and describe it, even better can you post it as a figure?
 
kuruman said:
What circuit? Can you be more specific and describe it, even better can you post it as a figure?. QUOTE]
The circuit that have an AC source and an induction coil . I mean when we close the circuit why the voltemeter detect a voltage between the coil"induced emf" if the the emf of the source has the same value and in an opposite direction?
 
OK, I see. The voltmeter cannot detect an instantaneous voltage, which is what you are talking about. You will get a better picture of the instantaneous voltage if you connect an oscilloscope across the induction coil.
 
kuruman said:
OK, I see. The voltmeter cannot detect an instantaneous voltage, which is what you are talking about. You will get a better picture of the instantaneous voltage if you connect an oscilloscope across the induction coil.
I got it ... So It only detects the voltage between the coil .
So what I said about the sum of the voltages is right ?
 
According to the Kirchhoff rule, the sum of the voltages around the closed circuit is zero at any time. That is always the case.
 
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