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# double check on something watch

1. can just check this... if the a.c. in a transformer is like a sine wave then the wave you see on a CRO across the secondary coil will be coherent, but out of phase by T/4, where T is the time period of oscillations.. is this correct?
2. I guess so,what bored are you doing??
3. I think mik1w is doing edexcel.

That's correct, but i haven't been taught this bit you stated "but out of phase by T/4", how do you know it is out of phase by that factor?
4. the T/4 factor must be the same as the transfromer ratio.. thats my guess.. i do edexcel and ive never been taught that
5. no but I want to clear it up... if the current is given by I=(I0)sint, then the flux linkage is hopefully proportional, the rate of change will mean you differentiate and then get an induced e.m.f. V=(V0)cost.. sin and cos are out by T/4. if the answer is yes then it will clear up transformers in my head a lot, if no then Ill scream
6. (Original post by mik1w)
no but I want to clear it up... if the current is given by I=(I0)sint, then the flux linkage is hopefully proportional, the rate of change will mean you differentiate and then get an induced e.m.f. V=(V0)cost.. sin and cos are out by T/4. if the answer is yes then it will clear up transformers in my head a lot, if no then Ill scream

I'm also not sure what the proportionailty would be between the current and the flux linkage... are you basing this on an equation?

Also.. Are you sure you can give the current as I = I0sin(t)? Do you not need a constant as in I=I0sin(k t) ? which when differentiated would give a cos graph as well but stretched vertically..
7. (Original post by mik1w)
no but I want to clear it up... if the current is given by I=(I0)sint, then the flux linkage is hopefully proportional, the rate of change will mean you differentiate and then get an induced e.m.f. V=(V0)cost.. sin and cos are out by T/4. if the answer is yes then it will clear up transformers in my head a lot, if no then Ill scream
Do you have the fullick textbook page 475?
8. I ask my teacher tomorow if no one has answered it by then. T/4 looks fine to me from that method of explannation.
9. (Original post by rieuwa)
Do you have the fullick textbook page 475?
nope .. what does it say?
10. hmmm.is it requierd by us,I think ocr require students to know this because i've seen it in an ocr paper,but I've never have seen it in the specification or the book ..as a matter of fact..can anybody post the graphs for the primary and the seconday ,I know that the secondary fulx would be pi out of phase with the original AKA the primary flux,but I'm not quite sure about it..anybody??!
11. I thought it would be pi/2 out of phase.
12. I though the emf is pi/2 out of phase
13. okay .. sorry I didnt read it properly.. what is the secondary flux, ? the flux that opposes the flux due to the primary coil? Lenz? argh! Im confused.
14. mmm mik dont panic it's not a high propability that edexcel want us to concentrate in this now ok
the ac current in the primary coil produces a magnetic flux ,now doesn't that induce a magnetic flux in the seconday which causes the emf to be induced in the secondary I'm just wondering about that..i'm not good at transformers they confuses me XXXXXX3

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