Which situation will induce the greatest current flow?

[JustinLiang]

Homework Statement

Question 30 from
http://www.bced.gov.bc.ca/exams/search/grade12/english/release/exam/0708PH_p.pdf

Homework Equations

I really don't know but here are some that I think can be used:
E=-N(flux)/t
B=(permeability of free space)(n)I

The Attempt at a Solution

I don't see how moving the magnets faster will create more current. However I understand why an increase in B can cause more current (though I cannot derive that with the use of formulas).

 

[collinsmark]

I really don't know but here are some that I think can be used:
E=-N(flux)/t

That's not quite right!
The induced emf isn't proportional the flux divided by time. Rather it is proportional to the change in flux divided by the change in time. It turns out that it makes a big difference.

[tex] \varepsilon mf = -N \frac{d \Phi}{dt} [/tex]

Which situation (of the possible four in the problem) causes the flux to change the most, within a given, short period of time?