Download Slide 1

Foundations of Technology
Resistors
Teacher Resource Unit 4 Lesson 4
© 2013 International Technology and Engineering Educators Association,
STEMCenter for Teaching and Learning™
Foundations of Technology
Objectives:
1.
2.
You will build a simple circuit to show
that resistors restrict the flow of
electrons.
You will be able to observe LED’s get
dimmer as you increase the resistance
in the circuit.
•Resistors have color
bands on them
•Colors are called the
“color code”
•4 bands on each resistor
•Band 1 = 1st Digit
•Band 2 = 2nd Digit
•Band 3 = Multiplier.
•Band 4 = tolerance
•Gold = 5%
•Silver = 10%
You will need the following parts from your kit:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Breadboard
220 ohms resistor (red, red, brown, gold)
1000 ohms resistor (brown, black, red, gold)
3300 ohms resistor (orange, orange, red, gold)
6800 ohms resistor (blue, gray, red, gold)
16000 ohms resistor (brown, blue, orange, gold)
2 @ LED (light emitting diode)
anode
cathode
9 volt battery lead
1 wire
Flat side Shorter lead
9 volt battery
Use this schematic to construct the experiment.
Flow of current
resistor
+
9 volts
cathode
anode
cathode
anode
Flow of current
Quick Check:
Your circuit should like this one.
1.
2.
3.
This circuit will light the LED’s.
The greater the electron flow the brighter the light.
Electrons flow from the battery through the LED’s,
then the resistor, then back to the battery.
The greater the resistance, the fewer electrons will
flow.
1.
2.
3.
4.
5.
6.
7.
8.
Start with the 220 ohm resistor in place.
Connect the 9 volt battery.
Observe the brightness of the LED’s.
Disconnect the 9 volt battery.
Replace the resistor with the 1000 ohm resistor.
Reconnect the 9 volt battery
Observe and compare the brightness of the LED’s.
Repeat steps 4 through 7 replacing the resistors
with the next greater resistor.
Troubleshooting:
1. If the LED’ does not light up, check to make sure it is in correctly.
2. Check the battery. Does it have voltage?
3. Are there any breaks in the circuit?
By completing this experiment, you should have
noticed the light from the LED’s grew dimmer as you
increased the value of the resistors.
In complete sentences, write what you learned about
resistors in a circuit.