# The circuit of the induction coil

• Aya Elsayed
In summary, when we turn off the circuit with an AC source and an induction coil, there will be an induced emf due to the changing magnetic field. The voltage across the coil will be maximum when the current is zero. The emf of the source and the induced emf have the same value but opposite directions, and they do not cancel each other out due to the Kirchhoff rule stating that the sum of voltages around a closed circuit is always zero. The voltmeter can only detect the voltage between the coil, not the instantaneous voltage, which can be better observed with an oscilloscope.
Aya Elsayed
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 ?

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.

Aya Elsayed

## What is an induction coil?

An induction coil is an electrical device that is used to produce high-voltage, low current electricity from a low-voltage, high current source. It consists of two coils of wire, a primary coil and a secondary coil, that are wound around an iron core.

## How does an induction coil work?

When an electric current is passed through the primary coil, it creates a magnetic field around the iron core. This magnetic field then induces a voltage in the secondary coil, which produces a high-voltage, low current output. This process is known as electromagnetic induction.

## What is the purpose of an induction coil?

An induction coil is used to step up or step down voltage in electrical circuits. It is commonly used in electronic devices, such as televisions and radios, to convert low voltage to high voltage for better signal reception. It is also used in industrial applications for welding and heating purposes.

## What factors affect the performance of an induction coil?

The performance of an induction coil is affected by the number of turns in the primary and secondary coils, the quality of the iron core, the frequency and amplitude of the input current, and the design and materials used in the construction of the coil.

## What are some common uses of induction coils?

Induction coils have a variety of uses in different fields. They are commonly used in medical equipment, such as MRI machines, for heating and welding in industrial processes, in high-voltage power supplies, and in electronic devices for signal amplification. They are also used in experiments and demonstrations to showcase the effects of electromagnetic induction.

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