# A-Level Physics Electromagnetic inductionWatch

#1
https://imgur.com/CdiWfCL

Having some trouble understanding the mark scheme for this question (Below)

https://imgur.com/FmOubxh

Shouldn't the pulses be rectangular, since a constant velocity means a constant rate of change of flux linkage, so the emf induced is constant?
0
9 months ago
#2
(Original post by Jayc3)
Attachment 752296
Having some trouble understanding the mark scheme for this question (Below)

Attachment 752296752298

Shouldn't the pulses be rectangular, since a constant velocity means a constant rate of change of flux linkage, so the emf induced is constant?
0
#3
(Original post by uberteknik)
Should be fixed now. If it still doesn't work the link is https://qualifications.pearson.com/c...e_20130116.pdf
Q16 part b

Mark Scheme:
http://pmt.physicsandmathstutor.com/...%20A-level.pdf
0
9 months ago
#4

Upload your images onto there and copy the lniks individually for each photo then paste each link into:

don't include the ..
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#5
(Original post by BTAnonymous)

Upload your images onto there and copy the lniks individually for each photo then paste each link into:

don't include the ..
Dw, here's the link to the paper:
https://qualifications.pearson.com/c...e_20130116.pdf

Q16 part b

Mark Scheme:
http://pmt.physicsandmathstutor.com/...%20A-level.pdf
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9 months ago
#6
I think it's something to do with the coil being a circle and not a rectangle (for example). If you imagine the circle cutting the field lines, there will be a change in flux as the area being cutting per second changes, whereas with a rectangle magnet or coil sheet, the area being cut per second is the same.

I hate EM induction so much lol.
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#7
(Original post by BTAnonymous)

Upload your images onto there and copy the lniks individually for each photo then paste each link into:

don't include the ..
Got both the paper the question is from and Imgur links, thanks for letting me know it existed lol
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#8
(Original post by BTAnonymous)
I think it's something to do with the coil being a circle and not a rectangle (for example). If you imagine the circle cutting the field lines, there will be a change in flux as the area being cutting per second changes, whereas with a rectangle magnet or coil sheet, the area being cut per second is the same.

I hate EM induction so much lol.
Ah that makes sense, so would I be correct in saying that if it was a rectangular coil the graph would be the way I described?
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9 months ago
#9
(Original post by Jayc3)
Ah that makes sense, so would I be correct in saying that if it was a rectangular coil the graph would be the way I described?
Yeah, the rectangle shape one is for a shape like a square or rectangle where the rate of change of area is constant but with the circle as it edges slowly into the field, the rate of change of area is increasing up until the radius I guess where it'll will reverse? That could explain why there's a very small drop to 0 for a small amount of time.

I hope that kind of makes sense. Not sure if it's right tbh but it seems fairly plausible.
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#10
(Original post by BTAnonymous)
Yeah, the rectangle shape one is for a shape like a square or rectangle where the rate of change of area is constant but with the circle as it edges slowly into the field, the rate of change of area is increasing up until the radius I guess where it'll will reverse? That could explain why there's a very small drop to 0 for a small amount of time.

I hope that kind of makes sense. Not sure if it's right tbh but it seems fairly plausible.
I remember one of my teachers saying something like that now that you mention it, I think your right lol thanks.
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9 months ago
#11
(Original post by Jayc3)
Attachment 752296
Having some trouble understanding the mark scheme for this question (Below)

Attachment 752302

Shouldn't the pulses be rectangular, since a constant velocity means a constant rate of change of flux linkage, so the emf induced is constant?
Flux linkage is dependent on the magnetic field passing through the area of the plane of the coil.

Think about the edge of the coil entering the linear part of the magnetic field between the poles. As it enters, the area of the coil entering the field is marked by a chord across the plane of the coil whose length increases until it equals the diameter of the coil. All the while the flux linkage is increasing in proportion to a sine curve (related to the circumference of a circle).

Faraday's and Lenz's laws apply: the magnitude of the induced emf tries to oppose the rate of increase of the flux entering the plane of the coil

When the coil diameter enters and passes the edge of the constant part of the field, the rate of change of flux linkage decreases until the whole coil has entered the constant part of the field. At this point, no lines of flux are cut and the emf induced is zero

This remains until the coil leaves the constant part of the field and traverses the edge of the poles, The induced emf tries to maintain the field and hence is in the opposite polarity to that when entering the field.
0
#12
(Original post by uberteknik)
Flux linkage is dependent on the magnetic field passing through the area of the plane of the coil.

Think about the edge of the coil entering the linear part of the magnetic field between the poles. As it enters, the area of the coil entering the field is marked by a chord across the plane of the coil whose length increases until it equals the diameter of the coil. All the while the flux linkage is increasing in proportion to a sine curve (related to the circumference of a circle).

Faraday's and Lenz's laws apply: the magnitude of the induced emf tries to oppose the rate of increase of the flux entering the plane of the coil

When the coil diameter enters and passes the edge of the constant part of the field, the rate of change of flux linkage decreases until the whole coil has entered the constant part of the field. At this point, no lines of flux are cut and the emf induced is zero

This remains until the coil leaves the constant part of the field and traverses the edge of the poles, The induced emf tries to maintain the field and hence is in the opposite polarity to that when entering the field.
Ah, that makes sense, thanks!
1
9 months ago
#13
(Original post by Jayc3)
https://imgur.com/CdiWfCL

Having some trouble understanding the mark scheme for this question (Below)

https://imgur.com/FmOubxh

Shouldn't the pulses be rectangular, since a constant velocity means a constant rate of change of flux linkage, so the emf induced is constant?
How do you deduce that the magnet is falling a constant velocity? There is no mentioning that the magnet is falling a constant velocity.
0
9 months ago
#14
(Original post by Jayc3)
https://imgur.com/CdiWfCL

Having some trouble understanding the mark scheme for this question (Below)

https://imgur.com/FmOubxh

Shouldn't the pulses be rectangular, since a constant velocity means a constant rate of change of flux linkage, so the emf induced is constant?
One more thing, even if the magnet is falling at constant velocity, the induced emf cannot be constant.
0
9 months ago
#15
There is an interesting animation that produced by MIT. The link is below.

Enjoy!
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