1 \begin{problem*}{22.48}
2 In Bohr's 1913 model of the hydrogen atom, the electron is in a
3 circular orbit of radius $r = 5.29\E{-11}\U{m}$, and its speed is $v =
5 \Part{a} What is the magnitude of the magnetic moment \vect{\mu} due to the
7 \Part{b} If the electron moves in a horizontal circle,
8 counterclockwise as seen from above, what is the direction of \vect{\mu}?
9 \end{problem*} % problem 22.48
13 The magnetic moment is defined on page 742 as
15 \vect{\mu} = I \vect{A}
18 The area swept out by our electron is just
23 The current is the amount of charge circling the nucleus in a unit
29 The time $\tau$ taken for an entire circuit is
31 \tau = \frac{\Delta x}{v} = \frac{2 \pi r}{v}
33 The current is then given by
35 I = \frac{\Delta q}{\Delta t} = \frac{q_e v}{2 \pi r}
38 Plugging $I$ and $A$ into our moment equation
40 \mu = \frac{q_e v}{2 \pi r}\cdot \pi r^2 = (q_e v r)/2 =
41 \ans{9.27\E{-24}\U{A m$^2$}}
44 The direction of the current is opposite the direction of the electron
45 (because the electron has negative charge), so the direction of