Cracking the SAT Physics Subject Test
Here’s How to Crack It
- The magnetic flux down through the loop increases as the magnet
is moved. By Lenz’s law, the induced emf will generate a current
that opposes this change. How do we oppose a change of more flux
downward? By creating flux upward. So, according to the right-hand
rule, the induced current must flow counterclockwise (because this
current will generate an upward-pointing magnetic field). As the
magnet is moved closer to the loop, the magnitude of the magnetic
field moving through the loop increases, as magnetic field is
inversely proportional to distance.