Download lesson 2 - Walden University ePortfolio for Mike Dillon

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.
Voltage  Current  Resistance V  I  R
•What are the units for voltage?
•What are the units for current?
•What are the units for resistance?
Ohm’s Law
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…
• 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?
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…
In a series circuit, you simply need to add
each of the individual resistances together to
get the total (equivalent) resistance.
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…
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:
Re  R1  R2  R3  ...
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.
R1  R2
Re 
R1  R2
1
1
1
1



 ...
Re R1 R2 R3
Equivalent Resistance
See if you can calculate the
equivalent resistance in each
of the following circuits.
40 
Equivalent Resistance
See if you can calculate the
equivalent resistance in each
of the following circuits.
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!