# Induced potential - when do you have to consider EM waves?

• yabb dabba do
In summary, the question is about calculating the electric potential induced by a changing magnetic field in a second conductor parallel to a 60 hz AC current. The Biot-Savart law and Faraday's law can be used theoretically, but the presence of EM waves from the alternating current may also induce a separate electric potential. The "quasi static" approximation can be used if the wavelength of the EM waves is much larger than the distance between the conductors, making it justifiable to ignore their effects. A suggested resource for further information is chapter 8 of a textbook on electromagnetics.
yabb dabba do
There's a long conductor carrying a 60 hz AC current. There's a second conductor parallel to the first current carrying conductor, and a hundred meters away from it.

I want to know what the electric potential induced by the changing B field is in the second conductor.

Theoretically I could use the biot-savart law to calculate B and then Faraday's law to calculate the induced electric potential from the changing B. However the alternating current also produces EM waves whose B field would induce an electric potential separate from that calculated by the biot-savart law as described above.

Is it justifiable to ignore the electric potential induced by the EM waves? Why/why not? Or am I just confused?

The usual rule of thumb is that you can use a "quasi static" approximation whenever the length scales are small compared to the wavelength of the EM waves. At 60 Hz the wavelengths are so much larger than 100 m that the quasi static approximation should be fine.

See this textbook, especially ch 8
http://web.mit.edu/6.013_book/www/book.html

jasonRF and vanhees71

## 1. What is induced potential?

Induced potential is the creation of an electric potential in a conductor due to a changing magnetic field. This is known as electromagnetic induction.

## 2. How is induced potential related to EM waves?

Induced potential is closely related to EM waves because it is a result of the interaction between electric and magnetic fields. EM waves are also generated through this interaction.

## 3. When do we have to consider induced potential?

We have to consider induced potential whenever there is a changing magnetic field in a conductor. This can occur when there is relative motion between a conductor and a magnetic field or when the magnetic field itself is changing.

## 4. What are the applications of induced potential?

Induced potential has various applications in our daily lives, such as in generators, transformers, and electric motors. It is also used in wireless charging, electromagnetic braking, and induction cooking.

## 5. How does induced potential affect electrical circuits?

Induced potential can cause changes in the current and voltage in electrical circuits. This can lead to power surges, which can damage electronic devices. Proper grounding and shielding are necessary to prevent these effects.

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