# AT Cycle 20*

## 1/10 - 1/15

M 1/10 & F 1/14

T 1/11

W 1/12

Th 1/13

### π΄β 1: M 1/10, π‘β 3: M 1/10a - electric field gradient

Re-quiz on Gauss's Law TODAY!

Today, we'll review getting the electric field with the gradient of the potential E=-βV . We'll do an example together. With any time remaining, we'll practice additional electrostatics AP problems. Look in Google Classroom for additional posted problems.

To think about the whole unit, here are the topics in electrostatics we have studied:

• Coulomb's Law

• Finding electric field

• E = F/q

• electric field integral (superposition of dq)

• Gauss's Law

• Electric potential energy of a configuration of charges

• Finding electric potential

• potential integral (superposition of dq)

• Path integral if we know electric field (compatible with Gauss's Law)

• Calculating field and potential due to non-uniform charge distributions (integrals)

You may watch a review video here:

Homework: Check out the Circuits Review Videos in preparation for the next unit which we will start the second week of January. Quiz on Electric Potential Energy & Potential Wednesday, January 12th.

### π₯ 1: T 1/11 virtual, π¨ 3: M 1/10b - electrostatics review

Today will be the last day to review electrostatics before your test next week. Catch up on any required problems you have not completed or find some extra electrostatics problems to practice from old AP exams.

Homework: Study for Quiz on Electric Potential Energy & Potential next class - Wednesday, January 12th. Check out the Circuits Review Videos in preparation for the next unit.

### β€οΈβ 1: W 1/12a, πβ 3: W 1/12 - equivalent resistance, β Positive Physics problems

Quiz on Electric Potential Energy & Potential TODAY!

Today, we'll review what you should know about circuits from last year. If you need to review videos from last year, then you can do that. There are several goals today:

• To understand the link between electrostatics and circuits.

• To understand and know how to use Ohm's Law.

• To understand why and how to calculate power lost in a resistor.

• To be able to solve simple series and simple parallel circuits with equivalent resistance.

• To be able to solve combination circuits with equivalent resistance.

The output is β Positive Physics unit 24: circuit analysis, "challenge 2" work problems only (just 4 problems) due Thursday at 10pm.

Homework: Electrostatics Assessment Tuesday, January 18th if we're back fully in person (or Wednesday, January 19th if still hybrid)! β Positive Physics is due on Thursday at 10pm. Make sure you know how to solve circuits with equivalent resistance by then. Only completion score counts, so try the problems till you get them right. No late work will be accepted. Watch the following two videos on Kirchhoff's Laws:

More Resources: Equivalent resistance is a very useful and fast way of solving circuits with multiple resistors and only one battery. I am assuming you know all about solving series, parallel, and combo circuits using equivalent resistance from last year. If you do not, you may want to review the material by looking at Electrical Circuits Lesson 4 (The Physics Classroom website), or watching videos on Series Circuits and Parallel Circuits (both by Dan Fullerton) and on a Combo Circuit Example (by Ron Call). Remember that the key to success with combo circuits is redrawing every time you combine resistors simply in series or simply in parallel. Work your way forward to find equivalent resistances and then work your way backward to get the currents through and voltage drops across each resistor.

### π 1: W 1/12b, π 3: Th 1/13 - equivalent resistance (2)

Today, we'll continue working through equivalent resistance problems. If you finish early, we'll get a head start on Kirchhoff's Laws.

Homework: β Positive Physics unit 24: circuit analysis, "challenge 2" work problems only (just 4 problems) due Thursday at 10pm. Electrostatics Assessment Tuesday, January 18th if we're back fully in person (or Wednesday, January 19th if still hybrid)!

### π΄ 1: F 1/14, π‘π¨ 3: F 1/14 - Kirchhoff's Laws & capacitor intro

Today, we'll start class by reviewing your past quizzes.

Then, we'll review Kirchhoff's Loop Rule and Junction Rule by doing an example problem. Although you may have already learned about the technique of using "equivalent resistance," this technique does not work well if we have more than one battery. Kirchhoff's Laws are a much more general technique for solving any circuit. We will be using this technique throughout this unit, so make sure you write down any questions you have and find the answers since it's very important you are an expert in using Kirchhoff's Laws. Pay special attention to sign conventions. Rewatch videos from last post if you need to.

Then, you'll practice Kirchhoff's Laws (loop rule and junction rule) by doing Kirchoff's Laws Intro HW. We'll also start to talk about capacitors.

Homework: Study for Electrostatics Assessment next class - Tuesday, January 18th if we're back fully in person (or Wednesday, January 19th if still hybrid)! Finish Kirchoff's Laws Intro HW due in βοΈ Google Classroom Tuesday.