PHYSICS: CHAPTER 35 Basic Circuitry Project – Lesson 2 My name is Georg Simon Ohm… I did a lot of work with circuits and resistance back in the day… Today we are going to review the law that was named after me as well as some of the basics of using the circuit simulator.

FORMULAS FOR-m-U-las Remember that Ohm’s Law is a formula. It can be used to calculate voltage, current, and/or resistance. What are the units for voltage? What are the units for current? What are the units for resistance?

Watch the following video clip to refresh your memory about Ohm’s Law… Is it vain for me to call it Awesome Guy’s Law? Ohm’s Law

Here’s a quick quiz… Ohm’s Law If the voltage stays the same in a circuit, what will happen to the current if the resistance goes up? Does Ohm’s Law apply to the whole circuit or individual elements of the circuit? If the resistance is the same, what type of graphical relationship exists between voltage and current?

Let’s also take a minute to review the process for calculating resistance in a circuit. The rules are different for series and parallel circuits… Equivalent Resistance In a series circuit, you simply need to add each of the individual resistances together to get the total (equivalent) resistance.

Let’s also take a minute to review the process for calculating resistance in a circuit. The rules are different for series and parallel circuits… Equivalent Resistance In a parallel circuit, the process is a little more difficult. Since the current has more paths to follow, the resistance actually decreases. There is a formula that you use…

FORMULAS FOR-m-U-las EQUIVALENT RESISTANCE For a series circuit, add the resistances together: For a parallel circuit, use the following formulas. The one on the left works for pairs. The one on the right works for more than two resistors.

See if you can calculate the equivalent resistance in each of the following circuits. Equivalent Resistance 40 

See if you can calculate the equivalent resistance in each of the following circuits. Equivalent Resistance 7.14 

Circuit Simulator Let’s review a few of features of the circuit simulator that you will need for today’s activity… We’ll highlight the key features on the next couple of slides…

Circuit Simulator Use the toolbar to get your meters. Also, make sure that you are in schematic mode.

Circuit Simulator Use the voltmeter to measure voltage. Place the probes on either side of the element when you want to measure voltage.

Circuit Simulator Use the non-contact ammeter to measure current. It will make life easier.

Circuit Simulator Right click and hold on an element to reposition it on the screen. Left click to make changes in the values or remove an element.

Getting Started on the Project It’s time to begin the activity. Be sure to ask Mr. Dillon if you have any questions… I know that he doesn’t have any equations named after him…and isn’t nearly as handsome as I am… …but then again…who is?

PHYSICS IS PHUN!