#### 3.2.1 Circular motion

By=50, normal to the velocity.

The basic equation expresses the identity of the
centripetal
force with *qvB*:

The trajectory is a circle, and the angular velocity
depends
only on the ratio q/m and the value of the field. The trajectory
radius,
*R=v/w*, depends on the *q/m* ratio, and is proportional to *v*
and inversely proportional to *B*. This kind of motion is
employed
in a device to measure atomic masses.

####