Visualizing the Electric Field
1. Measurement (+5):
a. (what) The quantity being measured is the voltage (+1).
b. (why) Because electric field cannot be measured directly (+1) with our equipment (Further reason see part 2).
c. (how) We use a power source and set the output voltage at a fixed value (+1),
then measure the potential difference from a reference point using a digital multimeter (+1) for different positions (+1).
2. 1-D Gauss's Law: the infinitely large parallel planes (+5):
The reason why we say that the two bricks can be treated as infinitely large planes is that: we are using current to mimic the behavior of electric field (thus we can measure the voltage to mimic the distribution of potential). The current from one brick stays only in the water and goes nowhere else but to the other brick.
a. Equation (+2):
From the equation of electric field for two parallel planes,
,
the potential is therefore
.
b. Data (+3).
- Uncertainty should be recorded/calculated (+1)
3. 2-D Gauss's Law: the infinitely long cylinder (+5):
a. Equation (+2):
Similarly,
,
and
.
b. Data (+3).
- Uncertainty should be recorded/calculated (+1)
3.5: Plotting (+5)
a. Format (+3)
b. Uncertainty (+2)
4. Fitting Results (+5):
a. Use correct equation for fitting (+1):
Especially, for case 2, V is proportional to ln(r), not exp(r).
b. Significant Figures (+1): The number of significant figures should remain the same after mathematical operation.
c. Uncertainty/error of fitting result (+2):
- Include the error (+1): Don't forget to report the uncertainty/error of the coefficients.
- Decimal Places (+1): The decimal places should be the same as the estimated value.
d. Plotted on the figures (+1).
5. Uncertainty Sources (+5).
6. Discussion & Suggestion (+5):
a. Comparison (+3).
b. Suggestion (+2).
7. 3rd trial (+10):
a. Data Table (+5):
- Units (+1).
- Enough sample (+4).
b. Contour Plot (+5):
- Plot (+3)
- Correct Contour Plot (+2)
8. Style (+5):
a. Submission Title (+1).
b. Start each question in a new page (+1).
c. Others (+3).
9. BONUS (+1):
Plot V vs ln(r), and there is a linear relationship!
10. Late Submission:
-3/hour