Texas Instruments CBL 2, Руководство по началу работы

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EXAS
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NSTRUMENTS
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NCORPORATED
G
ETTING
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TARTED WITH THE
CBL 2™ S
YSTEM
47
Teacher Section
Theory
The relationship between light intensity and distance can be described by a
function of the form
2
d
A
I
=
but there are so many potential sources of error that students are likely to see
discrepancies between theoretical predictions and the data. It is also very important
for students to realize that not all such discrepancies can be dismissed as
“experimental error.” This activity addresses this objective by attempting to identify
and compensate for experimental error.
The main sources of error your students should identify are:
♦
Errors in measuring distance.
♦
Extraneous light in the room.
♦ Errors in aiming the light probe.
♦ The light probe may not be zeroed – that is, with no light the light probe may
not read zero.
One way to convey the idea that not all discrepancies can be dismissed as
“experimental error” is by having students make light intensity readings using a
fluorescent bulb. Because fluorescent bulbs flicker, these measurements jump
around.
Answers
Sample data with sample answers:
1.
The left half of a “U.” (Intensity falls off rapidly as distance increases.)
2.
Distance Light Intensity
.5 .228
1 .070
1.5 .034
2 .026
2.5 .020
3 .014
3.5 .013