# Direction of flow of the electrons

1. Jul 11, 2007

### stmartin

Look at this picture.
What will happen if I move magnet among conductor in closed circular loop, so the magnetic field lines will be in opposite direction of the movement of the magnet? In which direction the electrons will flow and WHY?

2. Jul 11, 2007

### ranger

3. Jul 11, 2007

### olgranpappy

4. Jul 15, 2007

### stmartin

Explain why it is like that, like on the site you gave me please.

5. Jul 15, 2007

### olgranpappy

One way you can figure out how the electrons in the conductor move is by going to a different reference frame where it is the conductor that is moving and not the magnet. If in the original frame the magnet moved with velocity v. In the new frame the magnet is stationary and the electrons of the conductor are moving with velocity -v. Thus you can just use
$$\vec F = q\vec v \times \vec B$$
to find the force on the electrons and figure out their subsequent motion.

6. Apr 7, 2011

### srdickens

Of course you can also reverse the way the coil is wired and that will reverse the positive and negative output. There is a right and left way to wind coils, neither are the only correct way, its just winding it one way as the magnet approaches gives positive and negative one way and winding the coil the other way gives the opposite polarity output, assuming Im not mistaken here. I have wound coils and powered them with batteries using a compass to measure the north and south on the coils openings. And kept the polarity the same but wound the coil the opposite way and got a different north and south polarity at the same opening. So Im assuming here this works the same way with a magnet approaching a coil, its all according to which direction, left or right,, that the coil is wound,, gives you your polarity or magnetic field.