hectic18 said:
I've figured that A, C, E, F, G, H have no induction as there is no change in flux, but i dont know how to work out the others :S
What I do for induced currents is look at whether the magnetic field is increasing or decreasing. So for B, its going from a region of high magnetic flux density to lower flux density (as shown by the number of x's in the picture). Now looking at the trailing part of the coil (the part furthest away from the velocity arrow), we use the right-hand rule for induced currents.
That is: Thumb in direction of the direction of the motion of a positive charge. For B, this is to the left.
Fingers in the direction of the magnetic field TO BE PRODUCED. So this is the direction that will "oppose the change" in flux. For B, it's moving from stronger to weaker magnetic field. So it wants to oppose this change by strengthening the magnetic field that B moves into. How does it do that? In this case, by producing a field in the same direction as the one on the diagram (into the page).
So then, your palm faces the way the current will flow. As long as we remember that we are referring to the trailing part of the coil, the current in B from that point goes down, and follows clockwise around the coil.
The other coils can be done similarly.
(This is the 'positive test-charge' method.)
Hope that was useful
