physics: chapter 35 basic circuitry project – lesson 2 my name is georg simon ohm… i did a lot...
TRANSCRIPT
PHYSICS: CHAPTER 35Basic 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.
RIV ResistanceCurrentVoltage
•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:
...321 RRRReFor 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.
21
21
RR
RRRe
...
1111
321
RRRRe
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 SimulatorLet’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 SimulatorUse 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 ProjectIt’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!