How Does Lenz's Law Determine Current Direction in Moving Loops and Magnets?

[K3nt70]

Homework Statement

The figures below show two different situations where a current may be induced in a loop according to Faraday's Law, with the direction given by Lenz' Law. The magnetic field is shown by the x's in Fig. 2. Select ALL correct answers (i.e. B, AC, BCD) for the current in the loop. (The compass directions are defined in the usual way.)

http://img517.imageshack.us/img517/9134/prob07lenzlaw1us4.gif
http://img67.imageshack.us/img67/2264/prob07lenzlaw2pi7.gif

A) fig2: Loop moving North, induced current `b'.
B) fig1: Magnet moving West, induced current `a'.
C) fig2: Loop moving South, no induced current.
D) fig1: Loop moving West, induced current `a'.
E) fig2: Loop moving East, induced current `b'.
F) fig1: Magnet moving East, induced current `a'.

In figure 2, the magnetic field is strongest on the left, weakest on the right. As the magnetic field gets weaker, the current will flow clockwise (b) as the magnetic field gets stronger the current travels counterclockwise (a). since the magnetic field is the same if you move up or down, this means that C and E are true. Using the same principle for figure 1, (as they get closer together, the current flows counterclockwise, as they move apart, the current flows clockwise. This means that CEF should be the answer... What am i missing?

 

[K3nt70]

any insight into this one?

 

[Doc Al]

How do D & F differ?

 

[K3nt70]

jeez, why didnt i see that?:P So you would put your money on CDEF? i only have one attempt left at the question

 

[Doc Al]

That's what I'd put.

 

[K3nt70]

Correct! Thanks