More Resistors
Activity 6.2.3a
Magic of Electrons
© 2011 Project Lead The Way, Inc.
Variable Resistors
Potentiometers
Variable Resistors
A resistor whose value can be varied
mechanically between its minimum and
maximum values
Schematic Symbol
For
Potentiometers
Potentiometer Lab
On your activity sheet, draw a schematic diagram using a 3 volt DC
source that will power two LEDs in parallel, and includes a fixed resistor
on only ONE of those LEDs.
Build the circuit as shown so that you can easily insert various
resistors.
Schematic Symbol
For
Potentiometers
Potentiometer Lab
• Identify the color bands on the supplied
resistors and calculate the resistor
amounts.
• Rank your resistors 1 through 5, with #1
the resistor having the smallest amount of
resistance, and #5 with the greatest
amount of resistance.
• Follow the rest of the instructions on your
activity sheet, answering the questions as
work through the lab.
Finish this statement:
The __________resistance, the
brighter the light.
Variable Resistors
Thermistors
TEMPERATURE SENSITIVE resistors. INCREASING the
temperature DECREASES the resistance.
Schematic Symbol
For
Thermistors
Thermistor Lab
On your activity page, draw a schematic diagram of a series circuit
powered by 3 DC volts that contains an LED and a thermistor.
Follow the instructions in your activity worksheet to complete
this lab. Be sure to answer all questions completely, and to get
your instructor’s signature verifying your finished circuit.
Variable Resistors
Photoresistors
A light-sensitive device in which the internal
resistance changes with a change in light intensity
Schematic Symbols
For
Photoresistors
Either symbol can
be used
Variable Resistors
Photoresistors
Photoresistors
On your activity page, draw a schematic diagram of a series circuit that
uses 3 DC volts that will power an LED and is controlled by a photocell.
• Following the instructions found on your activity sheet, build the
circuit that you designed (you may want to space the photocell far
from the LED).
• Cover and then use the lamp to adjust the amount of light reaching
the photocell.
• Be sure to answer all the questions as you complete the activity.
Image Resources
Microsoft, Inc. (2009). Clip Art. Retrieved January 13, 2009, from
http://office.microsoft.com/en-us/clipart/default.aspx