# Appropriate Language when Discussing Faraday's Law

• tzonehunter
In summary, An emf is induced in the coil or across the coil due to the Faraday Law. However, unlike in the electrostatic case, this induced EMF is not a potential difference and cannot be measured directly using a voltmeter. Instead, the voltmeter will read a value that is proportional to the resistance of the coil and the current passing through it. This is often mistaken as the voltage across the coil, but in reality, the voltage is zero due to the presence of the voltmeter in the circuit. This is important to keep in mind when interpreting voltmeter readings in circuits involving induced EMF."
tzonehunter
Quick question, when discussing induce emf, would you state:

"An emf is induced in the coil..."
or

"An emf is induced across the coil..."

The reason I ask is that grammatically, it sounds proper to state "An electromotive force is induced in..." (something). However, an emf is a potential difference, which would occur across two points.

tzonehunter said:
"An emf is induced in the coil..."

Definitely. Some people use the term electromotance since emf is not a force and is measured in volts. The result of the Faraday Law is to create a current. This does imply the existence of an electric force which implies the existence of a potential difference. However in a closed good conducting loop having no definite beginning or end you cannot put a voltmeter across any part of it and get the same reading unless the length of the arc subtended is the same. One can think of the situation as being a distributed potential difference i.e., potential difference per unit length that exists around the entire loop.

tzonehunter said:
"An emf is induced in the coil..."

That's the way I see it used.

However, an emf is a potential difference, which would occur across two points.

No, that is true only in the electrostatic case. If you review an introductory calculus-based physics textbook, you will see the explanation for why the induced EMF is not a potential difference. In short, to have a potential difference you need two potentials so you can subtract them, and since you do not have a conservative force you cannot define an electrostatic potential.

rude man
tzonehunter said:
"An emf is induced in the coil..."
or

"An emf is induced across the coil..."

I thought perhaps this would be a useful illustration here... a photo I took of the innards of an electric skateboard hub motor (84mm tire diameter) with exposed stator core consisting of 12 wound coils/solenoids...

Mister T said:
That's the way I see it used.

No, that is true only in the electrostatic case. If you review an introductory calculus-based physics textbook, you will see the explanation for why the induced EMF is not a potential difference. In short, to have a potential difference you need two potentials so you can subtract them, and since you do not have a conservative force you cannot define an electrostatic potential.
Good one @Mister T.

It should further be pointed out that a voltmeter does not always indicate the voltage across its two probe tips. In the aforementioned case of a coil of resistance r surrounding a time-changing B field, if the probes are placed across some arc section θ of the coil, and if there is no B-dot field within the meter circuit (coil section θ, the meter and its probe wiring), the voltmeter will read rθI/2π, I = current. This is often mistaken as the voltage across the coil section θ but in reality that voltage is zero. The reason is that the meter wiring itself forms an alternate arc for coil section θ of the closed path. Furthermore, the voltmeter itself always reads actual voltage across itself assuming it forms a negligible length of the meter circuit. Cf. my Insight article on Dr Lewin's conundrum.

## 1. What is Faraday's Law?

Faraday's Law, also known as Faraday's electromagnetic induction law, states that when a conductor is placed in a changing magnetic field, an electromotive force (EMF) is induced in the conductor. This EMF can cause an electric current to flow in the conductor.

## 2. How is Faraday's Law related to appropriate language?

When discussing Faraday's Law, it is important to use appropriate language that accurately describes the scientific concepts involved. This helps to ensure clear communication and understanding among scientists and non-scientists alike.

## 3. What are some examples of inappropriate language when discussing Faraday's Law?

Some examples of inappropriate language when discussing Faraday's Law include using colloquial terms, incorrect terminology, or making unsupported claims. It is important to use precise and scientifically accurate language to avoid confusion and misinterpretation.

## 4. How can I ensure I am using appropriate language when discussing Faraday's Law?

To ensure you are using appropriate language when discussing Faraday's Law, it is important to thoroughly understand the scientific concepts involved. Additionally, you can consult reputable sources and peer-reviewed literature to ensure you are using accurate terminology and avoiding any common misconceptions.

## 5. Why is it important to use appropriate language when discussing Faraday's Law?

Using appropriate language when discussing Faraday's Law is important because it promotes accurate and clear communication among scientists and helps to avoid misunderstandings. It also helps to maintain the integrity and credibility of scientific research and discussions.

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