Thank you so much for all your magnetic field videos dude. Idk if you read comments but I really appreciate it all. I am revising for A-level physics (summer 2022) and your magnetic field videos explain things much better than my teacher did. I understand things a lot better now
By far the best EMF definition I've seen. By far the best series of explanation. Way better than my teacher's explanation. I understand what they've been saying eay better now
For the plane example at the end, surely the induced EMF will be 0 as when it's moving through the field the rate of change of flux density is 0. Surely you are only interested in the area swept out when it is entering the field ? Many thanks
Surely! Surely! 😂 There is no 'loop' of wire here - we treat the plane as just a piece of wire, which I should have made clearer. Therefore the emf=BLv, just like a wire.
@@ScienceShorts surely (😂) this means that the wire doesn't require a change in magnetic flux for an EMF to be induced which goes against what Faraday said. Is it different for a wire and a loop then ? If so why?
It is experiencing a change in flux as it's cutting flux lines. The confusion is really with the loop - the whole 'how much flux fills it' is just a way of explaining what really is going on: as both sides of a loop move through the field, they experience the same emf, so cancel each other out. Hence why you only get an emf when only one side is in the field.
When you are using Change in B in the initial eqn (around 14:00) the change is negative, so it should surely be -0.2Ts^-1 not 0.2Ts^-1, However this would make sense to cancel out when inputing the negative sign due to lenz's law. Is that why you haven't included it or have I made a mistake?
Maybe, but I think since he is giving an example in the context of AC current, which would imply the sign changes many times a second, there would be a greater incentive to know the magnitude and not worry about the sign. So at t=0.05, the sign would be, say, positive; at t=0.1, the sign would be negative. So it wouldn't really matter which sign is associated, and we can forget about Lenz's law and keep the equation to ε = ΔΦ / Δt in order to calculate just the magnitude. I know I'm well over a year late but I hope someone has already clarified this for you.
also you derived an eqation, E=BLv, why does this not apply in the second part of the video where the coil moves through the magnetic field perpendicularly and there is no induced e.m.f.?
4:58 In the aqa a level physics formula booklet, there is no negative sign for the change in flux/change in time. If they ask us to derive it, shall we put the negative sign or not? Many thanks for the videos, there saving my physics a level.
Many thanks:) In the aqa a level physics oxford revision guide it talks about back EMF but when you look in the specification there is no mention of it what so ever. Should I still learn it?
yes me too confused here. Line on graph with coil entering should be below x axis ( negative of positive gradient) , line of coil leaving, above 'flipped' as Sanjay put it. ..if we adopt negative sign in front of formula, right?
When the plane moves through the field lines why does the flux through it actually change? Isn't the whole 'area' of the plane in the field the whole time? Sorry if this is a silly question in just a bit confused.
+WhiteKyurem456 No, that's a valid question. When any wire/plane cuts flux i.e. moves perpendicularly to the magnetic field, emf is induced. It's only with a coil that we talk about an emf being induced if the flux "filling" the coil changes - this is just a model to describe what's happening. In reality, it's still just wires cutting flux.
Hi, Great video! You mentioned on the example of the coil that only when flux is changing an emf is produced, when the coil is fully in the magnetic field no emf is produced. But in the last example the plane is always fully inside the magnetic field, so how is an emf produced? Thanks
Remember that a coil is effectively 2 lengths of wire (we don't care about the parallel bits) - when they're both cutting flux, the both have the same emf induced in them, so no current can flow in the coil.
Omg I was litterelly watching the video now and I had the same question and then you answered it just in time .i have been planning to watch the vid for 3 days cause I've got a test .thank you soooo much for the video .you explain things very well and have made me gain my hope in getting a good grade in physics(:(:(:(:(:
Don’t hold me to this but I think it’s because it’s the horizontal velocity (so horizontal distance per second) and so multiplying it by the vertical distance creates the value of the area
@Science Shorts I don't understand why for a loop, an emf is only produced when it is entering or exiting a field, but for a straight wire, an emf is produced when it moves anywhere in the field. Could you explain? :)
Highly underrated channel.
Not anymore
@@armuhammad2148 why what happened
@@dimofn3854 just got bare subscribers init aha
@@dimofn3854 lol, as above now it's a famous channel, got wot it deserved
Yeah. I agree.
Thank you so much for all your magnetic field videos dude. Idk if you read comments but I really appreciate it all. I am revising for A-level physics (summer 2022) and your magnetic field videos explain things much better than my teacher did. I understand things a lot better now
brilliant explanation and derivation without this channel i would fail my a level
Beautiful derivation and explanation. I would watch urs over khan's especially for Physics
you've no idea how thankful I am for these!
These videos have been so helpful since I had to learn from home
ok.
3:00- faraday’s law
5:50- rate of change of flux=emf
15:00- faraday’s law
You my friend are going to get me a physics A level
Good luck for summer 2020:) in the same scary boat
@@rachiekimberly6800 lol you guys got it without sitting in exams
mmssuna thre true, somehow got the A in physics ;))
@@rachiekimberly6800 Wish that was me, lol. Got a B and had to "retake" the exams, I've got paper 2 tomorrow :/
@@imogeno4686 I got a B at first, before they went with teacher assessed grades and that one was an A. Good luck, you will do amazing!!!
By far the best EMF definition I've seen. By far the best series of explanation. Way better than my teacher's explanation. I understand what they've been saying eay better now
watching this 2 hours before my physics a level exam :)
Hope your exam went well
I am not gonna lie, you explain thing way better then my physics teacher.
why is there an emf induced when a plane flies through a magnetic field but not when a loop is moving in a magetic field?
What an amazing video. Really helped me understand induced emf. Thank you very much sir. Love from Malaysia ❤
I really like the connection to real life and the math correlation, food for the brain
You're a lifesaver man
Omg,i understand the Faraday‘ s law completely.
could you please do capacitors
brilliant video, just makes me want to cry.
For the plane example at the end, surely the induced EMF will be 0 as when it's moving through the field the rate of change of flux density is 0.
Surely you are only interested in the area swept out when it is entering the field ?
Many thanks
Surely! Surely! 😂
There is no 'loop' of wire here - we treat the plane as just a piece of wire, which I should have made clearer. Therefore the emf=BLv, just like a wire.
@@ScienceShorts surely (😂) this means that the wire doesn't require a change in magnetic flux for an EMF to be induced which goes against what Faraday said. Is it different for a wire and a loop then ? If so why?
It is experiencing a change in flux as it's cutting flux lines. The confusion is really with the loop - the whole 'how much flux fills it' is just a way of explaining what really is going on: as both sides of a loop move through the field, they experience the same emf, so cancel each other out. Hence why you only get an emf when only one side is in the field.
@@ScienceShorts excellent thanks for the help !👌
@@ScienceShorts my mind has officially been blown. Beautiful explanation!
It's about 12 days to my city and guilds exam and I've discovered this great channel. I'm sad
When you are using Change in B in the initial eqn (around 14:00) the change is negative, so it should surely be -0.2Ts^-1 not 0.2Ts^-1,
However this would make sense to cancel out when inputing the negative sign due to lenz's law.
Is that why you haven't included it or have I made a mistake?
Maybe, but I think since he is giving an example in the context of AC current, which would imply the sign changes many times a second, there would be a greater incentive to know the magnitude and not worry about the sign. So at t=0.05, the sign would be, say, positive; at t=0.1, the sign would be negative. So it wouldn't really matter which sign is associated, and we can forget about Lenz's law and keep the equation to ε = ΔΦ / Δt in order to calculate just the magnitude.
I know I'm well over a year late but I hope someone has already clarified this for you.
this is awesome thanks!
+Nathan Maghlaoui Glad it helps! :D
in the first diagram, if the 2 forces cancel out, how come you are able to find a change in mass from the scales if g is constant?
also you derived an eqation, E=BLv, why does this not apply in the second part of the video where the coil moves through the magnetic field perpendicularly and there is no induced e.m.f.?
did you find out the answer to this?
@@Trus-Ty sadly not
4:58 In the aqa a level physics formula booklet, there is no negative sign for the change in flux/change in time. If they ask us to derive it, shall we put the negative sign or not? Many thanks for the videos, there saving my physics a level.
The negative isn't important, as it's really just the magnitude of the change in flux we're concerned about.
Many thanks:) In the aqa a level physics oxford revision guide it talks about back EMF but when you look in the specification there is no mention of it what so ever. Should I still learn it?
I would, as it's just an application of Lenz's law - it's fair game.
Absolutely fantastic teacher! Thank you so much for the great lesson! 👏👏⭐️💖
When you talk about a negative EMF, is that just an EMF flowing in the opposite direction?
Wouldn’t the emf graph be inverted as the actual formula is e=-NBA/t so u would flip the graph for emf.
yes me too confused here. Line on graph with coil entering should be below x axis ( negative of positive gradient) , line of coil leaving, above 'flipped' as Sanjay put it. ..if we adopt negative sign in front of formula, right?
ah ok sorry Just seen at around 9.47 you added a minus sign to the emf on y axis ... all clear ! Thanks for a great vid!
thankyou for this!!
So so helpful! Thankyou so much :)
When the plane moves through the field lines why does the flux through it actually change? Isn't the whole 'area' of the plane in the field the whole time? Sorry if this is a silly question in just a bit confused.
+WhiteKyurem456 No, that's a valid question. When any wire/plane cuts flux i.e. moves perpendicularly to the magnetic field, emf is induced. It's only with a coil that we talk about an emf being induced if the flux "filling" the coil changes - this is just a model to describe what's happening. In reality, it's still just wires cutting flux.
Science Shorts So, any object moving through a B field will have an emf induced?
@@yoyoyoc3po any conductor
i have tears in my eyes. brilliant video!
Great derivation
Hi, Great video! You mentioned on the example of the coil that only when flux is changing an emf is produced, when the coil is fully in the magnetic field no emf is produced. But in the last example the plane is always fully inside the magnetic field, so how is an emf produced? Thanks
Science Shorts. Does that mean magnetic flux density isn’t the same all the way round the earth? How does the magnetic flux density change in the sky?
Remember that a coil is effectively 2 lengths of wire (we don't care about the parallel bits) - when they're both cutting flux, the both have the same emf induced in them, so no current can flow in the coil.
Omg I was litterelly watching the video now and I had the same question and then you answered it just in time .i have been planning to watch the vid for 3 days cause I've got a test .thank you soooo much for the video .you explain things very well and have made me gain my hope in getting a good grade in physics(:(:(:(:(:
Also is there a video explaining the BANwsin wt thing cause it confusing and I don't get it
do we need to remember derivation of faradays for AQA?
In the last example relating the plane in the magnetic field, why have you used the vertical length “w” instead of “A/w” for the horizontal length??
Don’t hold me to this but I think it’s because it’s the horizontal velocity (so horizontal distance per second) and so multiplying it by the vertical distance creates the value of the area
@@rachiekimberly6800 that makes sense
mmssuna thre lol I’ve not done physics in 4 months now oop
wow im a hamza khan too and i dont understand the same thing either
@Science Shorts I don't understand why for a loop, an emf is only produced when it is entering or exiting a field, but for a straight wire, an emf is produced when it moves anywhere in the field. Could you explain? :)
Because a loop is 2 lengths of wire connected together - if emf is induced in both, they cancel each other out.
does this apply to alevel OCR A
surely the emf at 14:20 would be 0.1 V as you have to divide by the change in time??
Nope.
0.2Ts^-1 the value that is used, has already taken into account time. So it is already used in the Eqn.
What if the coil is wound so that the area is increasing, so the coil is a cone inside of a cylinder?
Why rate of change of flux linkage is constant (straight line)? Why the graph isn't curve? Can you please explain it sir?I am really confused 🤔
The graph at 8:10 is straight lines because the velocity is constant. If it were accelerating the graph would have a changing gradient (curve)
Can anyone please help on why speed times width is the area in the equation at 16:19
Its not area, but area covered every second :)
Science Shorts thank you! I am in love with your channel btw. My exams are in two months and I couldn't have come across a better saviour than you!
+Kaishary Islam There is a better saviour - Jesus Christ - God with us ;)
*_I LOVE YOU_*
14:00
But it's 8 turns though...
isn't the emf = 0.02V?
I love you
we do have different equations for cie alevel but this does not make your videos any less helpful!
When is BANwsinwt used?
Rotating coil of wire - dynamo. It gives you the emf produced at time t.
Science Shorts isn't it simpler just to use EMF= N (BA/t) for that ?
Wouldn't ya know god made us intelligent...
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Weird face, mmmm lol
I love you