A ring rolling on a magnetic field what will be the emf induced
Answers
Answer:
Explanation:
Suppose we have a conducting disk of radius R
, rotating about its axis, with rotational velocity ω
. If surrounding the disk is a constant magnetic field parallel to its normal vector, a non-zero voltage appears between the center and the border of the disk.
I don't understand how this is possible: given that E=−d/dt∬ΣB⋅dS
, and since (taking Σ
= rotating disk)
d/dt∬ΣB⋅dS=d/dt(∥B∥ A)=0
Where A=πR2
is the area of the disk. It should follow that E=0 (which is the same as Vborder−Vcenter, right? And so V=0
.
I believe the answer should be V=∥B∥ A f
, with f=ω2π
, but I have no idea where this comes from, or why what I did yields an incorrect answer.
Also, could anyone illustrate the differences between E
, the induced EMF, and V here? They always seem to be the same thing
Explanation:
Faraday's apparatus for demonstrating that a magnetic field can produce a current. A change in the field produced by the top coil induces an emf and, hence, a current in the bottom coil. ... The same emfs are produced if the coil is moved relative to the magnet.