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© 2000, 2003 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
G
ETTING
S
TARTED WITH THE
CBL 2™ S
YSTEM
69
A c t i v i t y 5 – L i g h t s O u t !
Math Concepts
♦
Periodic functions
♦
Graphing and interpreting graphs
Science Concepts
♦
Data collection and analysis
♦
Period and frequency
Materials
♦
CBL 2™
♦
TI Graphing Calculator
♦
6-inch unit-to-unit link cable (or any length)
♦
TI light sensor
♦
1 non-fluorescent light source (regular light bulb)
♦
1 fluorescent light source
Introduction
A rocking chair moving back and forth, a ringing telephone, and water dripping
from a leaky faucet are all examples of
periodic
phenomena. They are called
periodic because they can be characterized by rhythmic cycles occurring in regular
time intervals. The time required to observe one complete cycle of the behavior is
called the
period
. The number of times the cycle occurs per unit of time is known as
the
frequency
.
In the following activities, you will use the CBL 2 and a light sensor to collect data
for two different types of periodic phenomena. You will then analyze this data
with your calculator to find the period and the frequency of the observed behavior.
Part 1
In this activity, you will point a light sensor towards a light source such as a light
bulb, window or an overhead lamp. To start, the end of the sensor will be covered
by your thumb. When the CBL 2 is activated, you will begin alternately lifting your
thumb from the sensor and re-covering it. Light intensity readings will be collected
by the CBL 2 and then displayed as a graph on the screen of your calculator.