Question

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html

The second figure says "(Magnetic field away from viewer)", but field lines are shown with dots (for arrow tips), not with plus signs (for arrow backs), and the induced current for the indicated direction of motion (rightwards) implies a magnetic field that goes *into the page*, not out of the page. So, figure needs modification, or am i missing something?

Answer 1

Correction: and the induced current for the indicated direction of motion (rightwards) implies a magnetic field that goes out of the page*, not into the page. Sorry.

So, figure needs modification, or am i missing something?

Answer 2

you're absolutely right. the induced current clearly creates a magnetic field that points toward the viewer, so by lenz's law (in reverse), the magnetic field is pointing away from the viewer. those dots should be crosses.

Answer 3

Thank you very much for replying.

The indicated direction of induced current is correct for the given motion of the wire (rightwards), and the *outward* magnetic field lines.

It is just that the text on the figure reads "(Magnetic field away from viewer)", written in blue, and that's the problematic part: It should read "(Magnetic field towards the viewer", or 'out of the page' for that matter :]

Here is my explanation (preparing notes for myself):
The direction of the magnetic field lines are out of the page (i.e. towards the viewer). As the wire is moved in the indicated direction (rightwards), the buildup of magnetic field can be visualized as the lines getting wrapped around the wire in the counter-clockwise direction. Then according to Lenz’s law, the induced current must produce a magnetic field in the opposite direction, i.e. clockwise direction.

-donovan