Name:

PHYSICS 232
Midterm 2, April 3 , 1998, 5:30pm-6:45pm
Instructor: P. Q. Hung

25 points for each problem. READ the problems carefully. SHOW CLEARLY YOUR WORK. DO NOT JUST write the answers down. ANSWERS WITHOUT EXPLANATION WILL BE GIVEN NO CREDIT.

Useful formulas (not necessarily applied to all problems below):

$F = k \frac{q_{1} q_{2}}{r^2}$

$\vec{E} = k \frac{q}{r^2} \hat{r}$

$\Phi = \oint \vec{E} \cdot d\vec{A} = 4 \pi k Q$

$U = \frac{1}{2} Q V = \frac{1}{2} C V^2$

$\vec{F} = I \vec{l} \times \vec{B}$

$d\vec{B} = k_m \frac{I d\vec{s} \times \hat{r}}{r^2}$

$\oint \vec{B} \cdot d\vec{s} = \mu_{0} I$

$\Phi_m = \int \vec{B} \cdot d\vec{A}$

${\cal E} = \oint \vec{E} \cdot d\vec{s} = -\frac{d\Phi_m}{dt}$

$B= \frac{\mu_0 I \Phi}{4 \pi R}$, $\Phi$: angle subtended by arc of circle of radius R

$f^{'} = f_{0}\frac{v \pm v_{o}}{v \mp v_{s}}$, v_o = speed of observer and v_s= speed of source.

$k_m = 10^{-7} T \cdot m/A$

$\omega = 2\pi f$

$v=\omega r$

$\mu_{0} = 4 \pi k_m = 4 \pi \times 10^{-7} T \cdot m/A$

$k = 8.99 \times 10^9 N\cdot m^2/C^2$

$\epsilon_0 = 1/4\pi k = 8.85 \times 10^{-12} C^2/N\cdot m^2$

$k = 8.99 \times 10^9 N\cdot m^2/C^2$

$\epsilon_0 = 1/4\pi k = 8.85 \times 10^{-12} C^2/N\cdot m^2$

$e= 1.6 \times 10^{-19} C$