Exam 1 Information

• Exam 1 on Wednesday, October 4th (A149 PSS)
  • Across from FRIB (Wilson side)
• 7pm-9pm
  • Arrive on time!
• I will provide a formula sheet (posted on Piazza already)
• You can bring one-side of a sheet of paper with your own notes.
• 4 questions - True/False, Essay, Graphing, Calculations

What's on Exam 1?

• Identify whether conceptual statements about $\mathbf{E}$, $V$, $\rho$, and/or numerical integration are true or false.
• Sketch and discuss delta functions in relation to charge density, $\rho$
• Calculate the electric field, $\mathbf{E}$, inside and outside a continuous distribution of charge and sketch the results
• Calculate the electric potential, $V$, for a specific charge distribution and discuss what happens in limiting cases

Could this be a plot of $\left|\mathbf{E}(r)\right|$? Or $V(r)$? (for SOME physical situation?)

1. Could be $E(r)$, or $V(r)$
2. Could be $E(r)$, but can't be $V(r)$
3. Can't be $E(r)$, could be $V(r)$
4. Can't be either
5. ???

We usually choose $V(r\rightarrow\infty) \equiv 0$ when calculating the potential of a point charge to be $V(r) = +kq/r$. How does the potential $V(r)$ change if we choose our reference point to be $V(R) = 0$ where $R$ is close to $+q$.

1. $V(r)$ higher than it was before
2. $V(r)$ is lower than it was before
3. $V(r)$ doesn’t change ($V$ is independent of choice of reference)

Electrostatic Potential Energy

Three identical charges $+q$ sit on an equilateral triangle. What would be the final $KE$ of the top charge if you released it (keeping the other two fixed)?

1. $\frac{1}{4\pi\varepsilon_0}\frac{q^2}{a}$
2. $\frac{1}{4\pi\varepsilon_0}\frac{2q^2}{3a}$
3. $\frac{1}{4\pi\varepsilon_0}\frac{2q^2}{a}$
4. $\frac{1}{4\pi\varepsilon_0}\frac{3q^2}{a}$
5. Other

Three identical charges $+q$ sit on an equilateral triangle. What would be the final $KE$ of the top charge if you released all three?

1. $\frac{1}{4\pi\varepsilon_0}\frac{q^2}{a}$
2. $\frac{1}{4\pi\varepsilon_0}\frac{2q^2}{3a}$
3. $\frac{1}{4\pi\varepsilon_0}\frac{2q^2}{a}$
4. $\frac{1}{4\pi\varepsilon_0}\frac{3q^2}{a}$
5. Other