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Re: [Phys-l] Question about Electromagnetic Induction



Hey folks,

The problem I posed looks innocent but is not a physical possibility. Magnetic field lines form closed loops. Hence, the space between the two circles cannot be devoid of B field. In fact, the field through this space should be directed opposite to the one within the inner circle. Thus, larger the radius 'a' LESSER is the NET flux through it and correspondingly lesser the dB/dt. Thus induced emf would decrease as 'a' increases.

It is inconceivable to think that emf would stay constant even if 'a' increases indefinitely!

Yesterday, I used a length of wire. Voltmeter, and the 'jumping ring' apparatus and verified that the induced emf indeed decreased as 'a' increased. Thanks,

~Hasan Fakhruddin
Instructor of Physics
The Indiana Academy for Science, Mathematics, and Humanities
Ball State University
Muncie, IN 47306