A student asked me a question that I couldn't satisfactorily answer and
could use your help. It concerns Faraday induction. Suppose we have a
single loop of wire lying in the plane of the page (or monitor screen) and
the loop is split -- that is to say, it's not a complete circuit. Also
imagine an increasing magnetic field into the page (monitor).
Faraday's/Lenz's law tells us that an emf will be induced such as to
produce a CCW current which generates a magnetic field out of the page. If
you envision the split in the loop being at the top of the page, then the
end of the loop to the left of the split would be at a positive potential
w.r.t. the other end.
Now here's the question. How large can this "split" become? For example,
suppose we open up the split so that it's as large as the diameter of the
loop -- what area does one use to calculate the magnetic flux? Does one
just imagine a "short" between the two open ends of the loop so that one
has a quasi enclosed area? Or suppose it's opened up even more so that the
loop becomes just a curved wire? At what point does the loop of wire no
longer enclose an area so that the problem can't be solved in this manner?
I look forward to your insights. Thanks, Wolfgang