te directions to be generated in these portions of the
loop, and these will tend to aid each other in causing a current to
circulate in the loop in the direction shown by the arrows associated
with the dotted representation of the loop. It is evident that as the
motion of the loop progresses, the rate of cutting the lines of force
will increase and will be a maximum when the loop reaches a horizontal
position, or at that time the two portions of the loop that are
parallel with the axis will be traveling at right angles to the lines
of force. At this point, therefore, the electromotive force and the
current will be a maximum.

From this point until the loop again assumes a vertical position, the
cutting of the lines of force will still be in the same direction, but
at a constantly decreasing rate, until, finally, when the loop is
vertical the movement of the parts of the loop that are parallel with
the axis will be in the direction of the lines of force and,
therefore, no cutting will take place. At this point, therefore, the
electromotive force and the current in the loop again will be zero. We
have seen, therefore, that in this half revolution of the loop from
the time when it was in a vertical position to a time when it was
again in a vertical position but upside down, the electromotive force
varied from zero to a maximum and back to zero, and the current did
the same.

It is easy to see that, as the loop moves through the next half
revolution, an exactly similar rise and fall of electromotive force
and current will take place; but this will be in the opposite
direction, since that portion of the loop which was going down through
the lines of force is now going up, and the portion which was
previously going up is now going down.

The law concerning the generation of electromotive force and current
in a conductor that is cutting through lines of magnetic force, may be
stated in another way, when the conductor is bent into the form of a
loop, as in the case under consideration: Thus, _if the number of
lines of force which pass through a conducting loop be varied,
electromotive forces will be generated in the loop_. This will be true
whether the number of lines passing through the loop be varied by
moving the loop within the field of force or by varying the field of
force itself. In any case, _if the number of lines of force be
increased, the current will flow in one way, and if it be diminished
the current will flow