Recall the machined copper from last class, with steady current flowing left to right through it
<img src="./images/machined_copper_2.png" align="center" style="width: 600px";/>
In the "necking down region" (somewhere in a small-ish region around the head of the arrow), do you think
1. $\nabla \cdot \mathbf{E} = 0$
2. $\nabla \cdot \mathbf{E} \neq 0$
Note:
* Correct Answer: A
Recall the machined copper from last class, with steady current flowing left to right through it
<img src="./images/machined_copper_2.png" align="center" style="width: 600px";/>
In steady state, do you expect there will be any surface charge accumulated anywhere on the walls of the conductor?
1. Yes
2. No
Note:
* Correct Answer: A
Quiz #1 was a fair assessment.
1. Strongly Agree
2. Agree
3. Neutral
4. Disagree
5. Strongly Disagree
I had enough time to complete Quiz #1.
1. Strongly Agree
2. Agree
3. Neutral
4. Disagree
5. Strongly Disagree
## Announcements
* Quiz #1 is graded. Average: 83%
* Would you like emailed grade reports after each quiz?
* Homework 3 is posted; Due Monday Jan 30th
* Turn in to Kim Crosslan by 4pm
* **No Class on Monday, Jan 30** - DC out of town
* Will be available by text and email
* Homework 4 will be posted
$\mathcal{E} = \oint \mathbf{E} \cdot d\mathbf{l}$
EMF ($\mathcal{E}$) is the line integral of the total force per unit charge around a closed loop.
The units of EMF are:
1. Farads
2. Joules
3. Amps, (that’s why current flows.)
4. Newtons, (that’s why it’s called emf)
5. Volts
Note:
* Correct Answer: E
Imagine a charge $q$ able to move around a tube which makes a closed loop. If we want to drive the charge around the loop, we **cannot** do this with E-field from a single stationary charge.
<img src="./images/loop_with_charge.png" align="right" style="width: 400px";/>
Can we drive the charge around the loop with some combination of stationary + and – charges?
1. Yes
2. No
Note:
* Correct Answer: B
A circuit with a battery with voltage difference $\Delta V$ is attached to a resistor. The force per charge due to the charges is $\mathbf{E}$. The force per charge inside the battery is $\mathbf{f} = \mathbf{f}_{bat} + \mathbf{E}$.
How many of the following statements are true?
<img src="./images/latex-image-1.png" align="center" style="width: 600px";/>
<img src="./images/latex-image-2.png" align="center" style="width: 600px";/>
A. 0 B. 1 C. 2 D. 3 E. 4
Note:
* Correct Answer: D