184_projects:chasing_thunderclouds [Projects & Practices in Physics]

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===== Project: Chasing a Thundercloud =====

You and your group are a team of storm chasers tracking a massive thundercloud moving across the plains and into the mountains beside the town of Lakeview. You grab your handy-dandy high voltage probe ([[https://www.atecorp.com/ATECorp/media/ProductImages/AdditionalImages/Tektronix-P6015A_R.png|like this one]]) and radio, then drive from your headquarters 250 m until you are directly under the storm cloud. Thankfully, your team already calibrated the voltmeter to 0 V when the storm cloud was very far away. From your training, you know that if the electric field is bigger than 3 MV/m (also called the [[https://en.wikipedia.org/wiki/Dielectric_strength|dielectric breakdown of air]]), the air will become a conductor and lightning will strike. You need to determine if a) you are safe from lightning under the thundercloud and b) if the lightning rod on top of the storm-chaser headquarters will be hit. The master storm chaser and part-time civil engineer, Edric Storm, tells you that the storm-chaser headquarters is 200 m tall.

<WRAP info>
===Learning Goals - Project 1A:===
  * Understand what the $\vec{r}$ is, how to calculate it, and how it relates to $\hat{r}$
  * Become familiar with the ideas of electric field and electric potential
  * Explain the differences between electric field and electric potential
  * Explain how electric field and electric potential are related
</WRAP>

Conceptual Questions:
  - What direction does $r_{source}$ point? What direction does $r_{obs}$ point? What direction does $r_{sep}$ point? Draw all of these on your diagram.
  - What would change about your solution if the thundercloud were the opposite charge (positive instead of negative or vice versa)? Does $r_{sep}$ change? Does the E-field change? Does the electric potential change?
  - What are the similarities & differences between electric field and electric potential?
  - What direction should the electric field point for positive charges? What direction should it point for negative charges?
  - What sort of assumptions did you make in this problem? How realistic are they?
  - How big is 1 Coulomb of charge? (how much charge is on a single electron, in a lightning bolt, on your socks when you rub the on carpet?)
  - What would change about your solution if you picked a different origin point? Pick a different origin & write out the calculation for the Electric Field on top of HQ.