An electron is moving with a velocity v in the direction
shown in the illustration. The electron enters a uniform magnetic
field B directed out of the page, marked by the dotted lines
On your whiteboard, make four illustrations of the electrons'
path inside the dotted region, one for each of the following field
(a) B = 0 inside
the region marked by the dotted-line
B field inside the region marked by the dotted-line
(c) medium strength B field
inside the region marked by the dotted-line
strong B field inside the region marked by the dotted-line
Comparing the motions of two different particles in one
Here, a uniform magnetic field is directed into the paper.
A hydrogen ion (a proton; shown to the left as +q) and an alpha
particle (two protons plus two neutrons; you get to draw it) enter
the field having the same velocity. Assume the field is large
enough so that the particles can execute complete circular trajectories
within the field.
On your whiteboard, calculate the relative sizes of the two
circular paths and sketch them to scale showing the direction of
travel for each. Recall equations for centripetal acceleration
and force. Give explanations for your reasoning.
Arons, A. (1996), Teaching Introductory Physics, Wiley:
NY, p. 105.
Cutnell, J. and Johnson, K. (1998), Physics, Vol. 2, Wiley:
NY, p. 634-6.