1. Name: Sue-Min
Date: 2013/01/13
Investigation: Light Intensity Investigation
Prior Knowledge: What do you already know? What did you research? Record sources of information in APA format.
Light intensity;
-Different measurements of light
-The light`s power in watts
-Brightness of the light
Light meter:
-Used to measure the amount of light
-To find light intensity of different sources of light
-Device to determine the measurement of the amount of light
Light
-Travels in a straight line
- Does not turn or curve
Electromagnetic spectrum:
-Red--- violet
Low frequency-- high frequency
Less/weaker --- stronger, more energy
1. Radio waves, Microwaves, Infra-red, Visible Light, Ultra violet, X-rays Gamma rays
Longer wave length, less frequency------------------------------short wave length, high frequency
Works Cited
Ask Kids. (n.d.). Retrieved 01 14, 2013, from What is light intensity:
http://answers.askkids.com/How_Stuff_Works/What_is_Light_Intensity
ePhotozine. (n.d.). Retrieved 01 14, 2013, from Guide To Using A Hand-Held Light Meter:
http://www.ephotozine.com/article/guide-to-using-a-hand-held-light-meter-4748
The Electromagnetic Spectrum. (n.d.). Retrieved 01 14, 2013, from The Electromagnetic Spectrum:
http://www.darvill.clara.net/emag/index.htm
TutorVista. (n.d.). Retrieved 01 14, 2013, from Light Measurement : http://physics.tutorvista.com/light/lightmeasurement.html#
Wikipedia. (n.d.). (Wikipedia) Retrieved 01 14, 2013, from Light Meter:
http://en.wikipedia.org/wiki/Light_meter
Wikipedia. (n.d.). (Wikipedia) Retrieved 01 14, 2013, from Light intensity:
ttp://en.wikipedia.org/wiki/Light_intensity
Sun and Light Unit booklet from Mr. Labreque
Variables: State the independent and dependent variables (one for each). State and briefly explain the controlled variables.
Independent: light (blue tinted light bulb, light bulb, candle) This is what we are going to change each
time when we do our experiment. The light source will affect the dependent variable, light intensity.
Dependent: light intensity, the brightness of the light
Controlled: the light measurer, 10cm of the distance between the light meter and the light source
Problem: Write a testable question that states the independent and dependent variables (one for each).
How do different sources of light affect the light intensity?
Hypothesis: Use third person command terms to make and explain a prediction that includes independent and dependent
variables, is justified using your prior knowledge and research.
The blue light bulb will have the strongest light intensity because in the spectrum, the blue light is
close to the violet; the violet is the strongest light in the geomagnetic spectrum. Fire will have the
lowest light intensity as red is the weakest in the spectrum. The normal light bulb will have higher
intensity than the red light bulb but will have weaker light intensity than the blue light bulb because
the light bulb color is yellow in the spectrum and yellow comes after red but before blue.
Materials: List what will you need.
Light bulb
Candle
Blue light bulb
Light measurer
Method: Use third person command terms and numbered steps.
1.
2.
3.
4.
Prepare all the materials needed.
Take one source of light and put it in front of you
Take the light measurer and turn it on
Point your light measurer toward the light source with a
distance of 10cm.
5. Check the light intensity of that source
6. Record the number on the table
Ruler
7. Repeat the process from 2-5 using the three different source of
light
Computer
Observations: Include a drawing, qualitative and quantitative observations, an Excel table for you raw data, a table and a graph
for your processed data, and show all calculations. For your tables and graphs, Include titles, headings, units, and grid lines for your
tables.
a)
Drawing
This drawing shows how we did our experiment. We laid down the light source on the table. We
used clay to make the light bulb stick on the table. Then we measured 10cm from the light bulb to
the light sensor. We turned the light meter on and made sure the light sensor was 10cm away from
the bulb and recorded the number showing on the light meter.
b)
Qualitative observations
Blue tinted light bulb
-Seems pretty bright
-Lets out a pretty light blue color
The bulb got really hot after a few minute when we turned it on
-The color looked like neon blue light
Regular light bulb
Really really bright
The color of the light looks yellow/white
Looks way brighter than the blue tinted light bulb
The light seems very strong (it shines a lot)
Couldn't see straight with my eye since it was too bright
Brightest out of the three light sources
Candle
Does not look that bright
Reddish, orangish flames
A hint of blue flames on the bottom of the flame: looks very hot
Was not that bright and I could see the light directly with my eyes because it was not that bright
compared with the regular light bulb.
The weakest light source out of the three
Smelled like fire, smoke
c)
Tables
Light source
Measurement: Trial 1
Measurement: Trial 2
Measurement: Trial 3
Candle
.498
.474
.523
Blue tinted light bulb
.950
.949
.953
Regular light bulb
.962
.964
.961
d)
Calculations
Light Source
Measurement (average)
Candle
.498
Blue tinted light bulb
.951
Regular light bulb
.962
e)
Graph
1.2
Graph 1: Effect of Light Source on
Light Intensity
Relative Unit
1
0.8
0.6
Measurement of the Light
Intensity
0.4
0.2
0
1. candle
2. blue tinted
light bulb
3. regular light
bulb
Light Source
Conclusion:
a) Summarize your hypothesis. Do your observations support your hypothesis? Explain thoroughly referring directly to specific data
points on your graph and table.
My hypothesis mentions how I think that the observation is related to the spectrum light. I said that
since the fire was the color of red, and red is the weakest light of the spectrum the light intensity
would be the lowest. I also said that the blue light would have the highest light intensity since it is
the closest with the violet. Since the regular light bulb is the color yellow I thought that it would have
more intensity than the fire but lower than the blue tinted light bulb.
I was half correct and half incorrect. As it is shown on the chart and the graph I was correct about the
fire having the lowest light intensity. However the blue tinted light bulb got lower than the regular
light bulb. The regular light bulb was the brightest among the three light sources. The light intensity
for the candle was 0.498, blue tinted light bulb was 0.951, and finally the regular light bulb had 0.962
for its light intensity. I can see that the light intensity of the candle and the tinted light bulb is pretty
wide. As my qualitative observation mentioned the candle did not even look that bright while the
blue tinted light bulb and the regular light bulb was pretty bright. The light intensity of blue tinted
light bulb and the regular light bulb has some difference though it there it is not that much. When I
did the experiment the regular light bulb seemed to be very brighter than even the blue tinted light
bulb but I can see there wasn`t that much difference.
b) Give two ways you could improve your method. Explain.
1. I think I could have improved the experiment by trying to be more precise when measuring
the candle. Since the candle was standing vertically we couldn't lay it down like the light
bulbs. We had to try to lift up the light meter and tried not to go forward than 10 cm. We
could have took more time and measured it somehow so it was exactly 10cm distance away
from the candle
2. We could have also improved the experiment better by choosing another independent
variable that can go well with each other. At the beginning my group thought that there were
three types of light bulb; regular light bulb, red tinted light bulb, blue tinted light bulb.
However there was only two so we had to suddenly replace the light source by using a candle.
This made our experiment a bit weird because the three sources of light wasn`t really related
to each other, other than the fact that there were two light bulbs.
c) Do your observations seem precise and accurate? Explain.
My observations seem precise for most of the numbers in the three trials. The candle Light`s three
light intensity is 0.498, 0.474, 0.523. This is the one in the three source that the number are not
precise that much because it has a pretty much difference between the 0.484, and the 0.523. The
light intensity for the blue tinted light bulb is 0.949, 0.50, and 0.953. These series of number is precise
because they are really close to each other and they have very little difference between them. The
light intensity for the regular light bulbs is 0.962, 0.964, and 0.961. The number for the regular light
bulbs is also precise because the numbers are pretty similar and there is no big difference between
some of them. This is because 0.961 and 9.964 don't have much difference that tells us that the
observations I took are really precise.
Accuracy;
In this experiment we could not have an accurate answer this we are measuring the light intensity.
However we did several things to try to make our results accurate. We measured the light intensity
using the light meter really carefully and tried to stick the light bulb really well do the table using
clay so it doesn`t role and go farther or closer to the light meter than 10cm. We also waited for the
numbers to show and wrote down the number that kept on showing the most so our results can be
accurate though it cannot be exactly accurate.
d) Based on your collected data, describe trends, patterns and relationships that you discovered.
Note: my experiment was about light source affecting the light intensity. It was a bit difficult to find each of these things because it
wasn`t something we can measure, for example like in cm if it was distance.
Pattern: I can see a pattern in my graph. The blue tinted light bulb and the regular light bulbs have
the similar light intensity. In the graph I can see the two graphs lined up similarly. This is a pattern
because it is repeating the similar light intensity.
Trend: There is one trend by looking at my graph. I can see that the blue tinted light bulb and the
regular light bulb have a trend because they have almost the same light intensity while the
candlelight have a lower intensity than both of them.
Relationship: The relationship is that different light sources have different light intensity. The candle
fire has 0.498 as its light intensity. The blue tinted light bulb has 0.951 for the light intensity. The
regular light bulb has 0.961 for its light intensity. As you can see, all of the light sources have
different light intensity. It is unlikely to have the exact same light intensity for different light sources.
e) Using the data, the research you did, your previous knowledge and scientific reasoning, explain the outcomes (What happened?
and Why
it happened?) of the inquiry?
The candle got the lowest intensity, than the blue tinted light, and finally the regular light bulb had
the most intensity. When I first saw the blue light bulb I thought that the light was actually blue
instead of a blue tinted light bulb. After I figured that out I thought that the blue tinted light bulb
would be than less than the regular light bulb, because the tint is covering some of the regular light
bulb and only letting out some to make the color blue. Because of my misunderstanding the
outcome was different from what I thought but if I knew that it was a blue TINTED bulb I would have
said that the blue tinted bulb would be the 2nd light source to have the biggest light intensity instead
of being the first. In my previous research I learned that in the geomagnetic spectrum the colors go
from red to violet light. The red is the weakest and the most powerless light. The violet is the
strongest light in the spectrum. As I thought, the fire had the lowest light intensity among the other
sources and got 0. 498. The blue tinted bulb got the highest light intensity after the normal light
bulb. This is because of the tint. As I said the tint makes the light intensity less because by covering
the bulb with the tint it does not make the light as bright as the original bulb. The brightest was the
normal light bulb, which was like the color yellow. In the geomagnetic spectrum, the yellow is after
the red and has more short wave length and high frequency than the red so I think the light intensity
was higher than the candle.
Conclusion- (lowest intensity to strongest light intensity) candle fire, blue TINTED light bulb, and a
regular light bulb