Is the term loop loosely defined in Faraday's law?

[LightFantastic]

Is the term "loop" loosely defined in Faraday's law?

A voltage will be induced in a loop of wire when the magnetic field flux through the loop changes

If you're reading this, you probably know what happens when you hook up the leads from an oscilloscope to a microphone. Nothing, lol. There needs to be relative motion between the voicecoil and the permanent magnet for you to view any voltage fluctuations.And here is the origin of my confusion,

Disconnect the leads. The voicecoil is now open ended. In other words, it is NO LONGER a true loop. Will a voltage still be induced? Also, voltage is a measure between two points or ends in the case of a voice coil. How am I supposed to find the "ends" in a circle?

 

[Simon Bridge]

You mean - does the loop have to be closed?
No.

 

[cabraham]

Without the loop closed there will be a voltage and current induced in the loop. By the way, the scope is a very high input impedance and having it connected is very close to having the loop open. With the loop closed, the voltage around the loop gets smaller and the current gets bigger. The voltage around the loop is defined for a specific path. If we start at point A, go around the loop once and end on the same point, there is a definite voltage along that path.

Claude

 

[vk6kro]

A voltage will be induced in a loop of wire when the magnetic field flux through the loop changes

If you're reading this, you probably know what happens when you hook up the leads from an oscilloscope to a microphone. Nothing, lol. There needs to be relative motion between the voicecoil and the permanent magnet for you to view any voltage fluctuations.And here is the origin of my confusion,

Disconnect the leads. The voicecoil is now open ended. In other words, it is NO LONGER a true loop. Will a voltage still be induced? Also, voltage is a measure between two points or ends in the case of a voice coil. How am I supposed to find the "ends" in a circle?

Using a moving coil "dynamic" microphone, you should get an output if you talk into it and this may be visible on the oscilloscope trace if you have enough gain in the oscilloscope.

These microphones are now fairly rare and you might be using an "electret" microphone which requires a source of DC voltage to make it work.

 

[alphy]

I would say that the term "loop" in Faraday's law is not loosely defined, but rather it is specifically defined in terms of a closed circuit. In the context of Faraday's law, a loop refers to a complete circuit or closed path through which the changing magnetic flux can induce a voltage.

In the example given, the voicecoil may no longer be considered a loop since it is open-ended and not a complete circuit. In this case, Faraday's law would not apply and no voltage would be induced. This is because the changing magnetic flux cannot create a closed path through the open-ended voicecoil.

It is important to note that the term "loop" in Faraday's law is not meant to be taken literally as a physical loop or circle, but rather as a conceptual closed path that allows for the induction of voltage. Therefore, in this context, the ends of a loop would refer to the two points or ends of a closed circuit, not necessarily the physical ends of a circular object.

In summary, the term "loop" in Faraday's law is specifically defined as a closed path or circuit, and it is not loosely defined. It is important to understand the concept of a closed circuit in order to accurately apply Faraday's law in practical situations.