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direction induced current in a loop of wire (1 Viewer)

m00

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ok the question:

'In what direction, clockwise or anticlockwise is the induced current in the loop of wire?'



It has to do with eddy currents and the teacher wont tell us the answer so yeah im stumped.. all I know is that the direction of the magnetic field is INTO the page (using the right hand push rule)? but how do we use that to find out of it's clockwise or anti clockwise

I think its clockwise because I read somewhere that the direction of the current in a loop is the same direction as the direction of the magnetic field or somthing to that extent anyway so I just presumed it is clockwise. anyone have any ideas or input? enlgihten me =)

btw there are 4 different questions to this question, the one i showed is the first one, page 131 in the second Edition Jacaranda Physics HSC COURSE book
 

undalay

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something has to be happening for a current to be induced.
I don't understand the diagram, current is increasing? doesn't make sense.
 

m00

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thats exactly what it says/has in the book, it has the direction says 'I is increasing'
 
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Steth0scope

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By right hand grip rule, there are dot's on the right of the straight wire and x's on the left hand side of the wire i.e. the magnetic field created by the straight wire comes out of the page on the right of the wire and goes into the page on the left.

Now, the magnitude of the current in the straight wire is increasing which means that the magnetic fields around the straight wire begin to expand.

This has the effect of increasing the amount of magnetic field (flux) threading the loop of wire. The key thing is that there is an increasing amount of x's (magnetic field lines into the page) threading inside the loop of wire (due to the increasing current in the straight wire).

The loop of wire tries to counter-act this by giving rise to a current that reduces the amount of x's inside the loop (i.e. magnetic fields into the page). This is achieved by setting up a current in the loop that produces dot's inside the circle. By right hand grip rule, this occurs if the current travels anti-clockwise.

It sounds pretty complicated but its really not. If you don't get something PM me and I'll try and answer your question.

EDIT: I noticed the current was increasing not decreasing and fixed it up.
 
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m00

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I got it =)
makes sense to me now but still kind of pondering the 'I increasing' and 'I decreasing' for 'I increasing' I basically put the opposite direction and for 'I decreasing' I put the same direction

enlgihten me again please? :)
 

gorillaunsw

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m00 said:
I got it =)
makes sense to me now but still kind of pondering the 'I increasing' and 'I decreasing' for 'I increasing' I basically put the opposite direction and for 'I decreasing' I put the same direction

enlgihten me again please? :)
the change in current is opposed by the emf...this is due to the conservation of energy...

hence wen I increases in that image the coil will experience a greater force into the page...due to the right hand rule....therefore an induced current will be created in order to oppse this change...and hence will travel in an anticlockwise direction to make field lines come out of the page in the coil itself.

thus wen the I decreases the opposite effect will happen...and so the coil will want to increase its magnetic flux in the coil in order to remain at its current flux..

if you need any more help just post again
 

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