Flux linking (and de-linking?)

[sdfsfasdfasf]

Homework Statement

x

Relevant Equations

x

Initially the current is non-zero therefore we have a magnetic field present, and at the end there is no current therefore there is no magnetic field present.
When we open the switch, and the current drops to 0, there is a change in the magnetic flux of B, as the field from A has gone. This change is intuitively a decrease, right?

If so, why does the markscheme state that "Flux links to B", should it not be "Flux de-links from B"? Or am I being pedantic?

 

[Steve4Physics]

If so, why does the markscheme state that "Flux links to B", should it not be "Flux de-links from B"? Or am I being pedantic?

The mark scheme is simply stating that the flux (created by the current in coil A) is linked to coil B.

This is always true - whether the flux is constant, increasing or decreasing.

By the way, you haven't really answered the question.

1) You haven't explained (in terms of magnetic flux) the first observation: why the lamp is initially off - even though the switch is closed.

2) And you haven't made the key point - that a changing flux induces an emf (or induces acurrent).

 

[sdfsfasdfasf]

I wasn't answering the question in my post!
I just wanted to know what is meant by the phrase "links to", and it seems that its a little more complicated than expected, could you talk about it a little more, particularly the bit where you said "this is always true". How can we distinguish this from a changing flux?

 

[Steve4Physics]

I wasn't answering the question in my post!

You gave the question immediately followed by what appears to be your answer. So I assumed that it was your answer! What was the purpose of what you wrote, if it was not an attempt at an answer?

You then gave the mark scheme followed by a question about the mark scheme.

I just wanted to know what is meant by the phrase "links to", and it seems that its a little more complicated than expected, could you talk about it a little more, particularly the bit where you said "this is always true".

Coils A and B share the same iron core. As a result, the magnetic flux (created by the current in coil A) is linked to coil B.

If the flux through A increases, so does the flux through B.
If the flux through A decreases, so does the flux through B.
If the flux through A is constant, so is the flux through B.

Any change in the flux through B induces an emf in B.

I don't think I can add anything further.

 

[sdfsfasdfasf]

My confusion was around the phrase "links to", if instead we use "flux in A is linked to B" that makes a lot more sense to me. I was misunderstanding and thought "links to" had something to do with increasing flux, when it dosesn't. Thank you Steve.

 

[Gavran]

“as the (magnetic) flux links to B” is a correct phrase.

The magnetic flux generated by the coil A exists in coils A and B and it makes a connection between coils A and B in a particular way. So the magnetic flux produced by the coil A links coil A to coil B and it can be said “as the (magnetic) flux links to B”.

 

[sdfsfasdfasf]

I agree its a correct statement, however my interpretation (incorrect) was that "links to" refers to increasing flux exclusively. When we cut the current, that reduces the flux present right?