THE STUDY OF FLASHLIGHTS AND THE AMOUNT OF LIGHT THAT DIFFERENT SOURCES OF

LIGHT PRODUCE

Katrine Andersen

Cary Academy

ABSTRACT

The purpose of this study was to determine if the distance that the flashlight is held effects and

determines how much light that the light probe will collect. Visible light, which is commonly referred to

as light, is part of the electromagnet spectrum, which ranges from radio waves to gamma waves. A

flashlight was placed several different distances away from the light probe it was then turned on. It

was determined that when the flashlight was placed 1 cm away from the light probe the light probe

collected more light than when farther away. It was concluded that the reason that less light is

collected when placed farther is due to the spreading of the light.

INTRODUCTION

Katie Barbery at Cary Academy School tested different batteries and the voltage loss. In addition,

Katie tested batteries to determine which battery had the greatest voltage loss and which battery had

the least voltage loss. Katie used different brands of batteries and different types of batteries like

AAA, AA batteries and C batteries. The first experiment that Katie Barbery conducted was testing the

voltage of different brands of AA batteries. Katie did this by using a Laser FX. The rest of Katie’s

experiments were similar to Katie’s first experiment. The second experiment was conducted using a

coin sorter instead of a Laser FX and replacing AA batteries with C. In the third experiment, it was

repeated, but this time was conducted using a walkie-talkie and nine voltage batteries (3 for each

test). Experiment 4 was similar to the first one but was instead conducted with a flashlight and D

batteries. For the fifth experiment the same process as the other experiments were done but using a

portable radio and AAA batteries. From the results of the experiments, Katie Barbery learned that

Raovac had the greatest voltage loss compared to all the other batteries that Katie used in her

experiments. Katie also concluded that Energizer batteries had the least voltage loss compared to the

other batteries.

What exactly is light? Many people over the years have wondered what exactly light is. Visible light,

most commonly known as light is part of the electromagnet spectrum, which ranges from radio waves

to gamma waves. Visible light is not different from the other parts of the electromagnet spectrum

however, the one exception to this is that human eyes can detect and see the visible rays as well as

gamma rays. Electromagnetic radiation can also be described in terms of a stream of photons.

Photons are massless particles each travelling with wavelike properties at the speed of light. A

photon is the smallest quantity (quantum) of energy that can be transported and it was the realization

that light travelled in discrete quanta that was the origins of Quantum Theory. Light traveling along its

straight path is known as a light ray. However, a collection or bundle of light rays make up a light

beam. A candle flame or an electric bulbs filament produces light because these items produce heat

and energy. However, there are cold sources of light such as a fluorescent tube. Light is also a form

of energy.

Figure 1. This diagram shows what happens when the sun’s rays hit a surface and then reflects off.

Humans use batteries for many appliances and everyday use. However, no one takes the time to

think why batteries supply energy and what makes a battery a battery. The anode (-), cathode (+),

and the electrolyte are the 3 parts that make up a battery. The anode is also commonly referred to as

the negative side and the cathode is commonly known as the positive side. To create energy or

electricity batteries are installed in a circuit. A circuit can also be known as the flow of electrons

through a conductive path like a wire. The chemical reaction in the battery causes a buildup of

electrons at the anode. This results in an electrical difference between the anode and the cathode. It

can also be thought of an unstable build-up of the electrons. The electrons want to rearrange

themselves to get rid of this difference. However, they do this in a certain way. Electrons repel each

other and try to go to a place with fewer electrons. In a battery, the only place to go is to the cathode.

However, the electrolyte keeps the electrons from going straight from the anode to the cathode within

the battery. When the circuit is closed, the electrons will be able to get to the cathode. The electrons

go through the wire, lighting the light bulb along the way. This is one way of describing how electrical

potential causes electrons to flow through the circuit. A battery has to be hooked up to a circuit so

that he anode and the cathode are connected and then the anode to the cathode.

+-

+ -

Batteries

Figure 2. This shows the way that the batteries are hooked up to the circuit, first the cathode (+) to the anode (-) and the anode

(-) to the cathode (+) then the cathode (+) to the anode (-).

What exactly is electricity and what forms of electricity are there? Electricity forms at the basis of a

nerve signal. Human eyes receive light rays and turn them into tiny electrical signals that pass along

nerves into the brain and the rest of the body. Our whole awareness and ability to think and move

depends on little electrical signals whizzing around the nerve pathways inside the brain. The

phenomenon associated with stationary or moving electric charges is called electricity. Electric

charge is a fundamental property of matter and is borne by elementary particles. In electricity, the

particle involved is the electron, which carries a charge designated by convention as negative. Thus,

the various manifestations of electricity are the result of the accumulation or motion of electrons. An

example of electricity is lighting. Lightning is actually a discharge of static electricity; static electricity

is where friction transfers charged particles from one body to the other. Magnetism and electricity are

related in many different ways. Electricity and Magnetism are two aspects of electro-magnetism which

is the science of charge and of the focus and fields associated with charge. Electricity and magnetism

were thought for a long time to be separate forces, not until the 19th century was they finally treated

as interrelated phenomena. Electric and magnetic forces can be detected in regions called electric

and magnetic fields. These fields are fundamental nature and can exist in space far from the charge

or current that generated them. The electric force in particular is responsible for most of the physical

and chemical properties of atoms and molecules. Electric forces are produced by electric charges

either at rest or in motion. Magnetic forces on the other hand are produced only by moving charges

and act solely on charges in motion. Electric charges are of the two general types, positive and

negative. Electric charges are called electricity, so all electric charges are electricity and vice versa.

MATERIALS AND METHODS

In these experiments a Mini Maglite flashlight, Husky flashlight, LED Technology flashlight, timer, light

probe, ruler, table, computer, green expo marker, red expo marker, black expo marker, blue expo

marker, silver sharpie, black sharpie, and a red sharpie were used.

Different brands of flashlights were tested to see, which one could produce the most amount of light.

First, the Husky flashlight was placed 5 cm away from the light probe and then was turned on and the

light probe collected the amount of light that the flashlight produced. The information was recorded

into the computer and repeated 2 more times. When done 3 times an average was determined. Then,

the LED Technology flashlight was placed 5 cm away from the light probe, the flashlight was then

turned on. The light probe collected the amount of light that the flashlight produced. The data was

recorded into a computer and the process was repeated 2 more times. Averages of the three were

measured and were calculated. Lastly, the Mini Maglite flashlight was placed 5 cm away from the light

probe and turned on. The data was recorded into a computer and the process was repeated 2 more

times, an average of the 3 was calculated.

A flashlight was placed different distances away from the light probe to see if it affected the amount of

light that the light probe picked up. The flashlight was placed 1 cm away from the light probe and

then turned on. The light probe collected the amount of light that it produced. The information was

recorded and repeated 2 more times. When done 3 times an average was determined. The flashlight

was placed 8 cm away from the light probe, it was then turned on, the light probe collected the

amount of light that it produced. The data was recorded and the process was again repeated 2 times

then taken an average. Then the flashlight was placed 15 cm away from the light probe and turned on

the data was recorded. The process was again repeated 2 times and an average was determined.

Lastly, the flashlight was placed 25 cm away from the light probe, the data was recorded and the

process was repeated 2 times. When done 3 times an average was determined.

Different brands of batteries were tested to see if it affected the amount of light that the flashlight

produced. Energizer batteries were placed in a flashlight. The flashlight was then placed 5 cm away

from the light probe. The light probe collected the amount of light produced. This was repeated 2

more times with the Energizer batteries, after 3 times an average was determined. Then, Everyday

Super Heavy Duty batteries were placed in the flashlight. The flashlight was then placed 5 cm away

from the light probe and turned on. The light probe collected the amount of light that the flashlights

produced and this was done 2 more times, an average was determined. After, Everyday Gold

batteries were placed in the flashlight, the flashlight was then positioned 5 cm away from light probe,

the light probe collected the amount of light that was produced. This was repeated 2 more times and

then an average was determined. Lastly, Kodak batteries were placed in the flashlight. The flashlight

was positioned 5 cm away from the light and the light probe collected the amount of light that it

produced. This was done 2 more times and an average was determined.

A flashlight was left on for different amounts of time to see if it affected how much light it produced.

The flashlight was placed 5 cm away from the light probe and then turned on for 1 sec. Then it was

turned on and kept on for 60 sec the light probe collected how much light was produced this was

repeated 2 more times and an average was determined. After that, it was then turned on for 120 sec

the light probe collected the amount of light that it produced this process was repeated 2 more times

than an average was determined. Then the flashlight was left on for 240 sec and the light probe

collected the amount of light that it produced this process was done 2 more times, then an average

was determined. Lastly, the flashlight was left on for 500 seconds the light probe collected the amount

of light that was produced and the data was recorded, this was repeated 2 more times, and an

average was determined.

A flashlight was placed different distances away from a mirror to see if it affected the amount of light

that the mirror reflected. The flashlight was first placed 1 cm away from the mirror the light probe

collected the amount of light that reflected. The data was recorded and the process was repeated 2

more times, an average was then determined. Then the flashlight was placed 6 cm away from the

mirror, the light probe collected the amount of light that was reflected off. The data was recorded and

the process was repeated 2 more times an average was then determined. After that, the flashlight

was placed 18 cm away from the flashlight, the light probe collected the amount of light that the mirror

reflected. The data was recorded and the process was repeated 2 more times, an average was

determined. The flashlight was then placed 30 cm away from the mirror and the light probe collected

the amount of light that was reflected. The data was recorded and the process was repeated 2 more

times, an average was then determined. After, the flashlight was placed 40 cm away from the mirror

the light probe collected the amount of light that was reflected. The data was recorded and the

process was repeated 2 more times. An average was determined.

Different brands of soap were placed over the lens of a flashlight to see if it affected the amount of

light that the flashlight produced. The experiment was first conducted with using no soap, the

flashlight was placed 5 cm away from the light probe and the amount of light the flashlight produced

was recorded, this was repeated 2 more times and then an average was determined. Soft soap was

placed over the lens of the flashlight and then the flashlight was placed 5 cm away from the light

probe. The amount of light produced was recorded and the process was repeated 2 more times. An

average was then determined. Then Dial soap was placed over the lens of the flashlight. The amount

of light was recorded and the process was repeated 2 more times. An average was then determined.

After that Up and Up soap was placed over the lens of the flashlight the light probe collected the

amount of light produced and the data was recorded. This process was repeated 2 more times, an

average was then determined.

Different colors of plastic were placed over the flashlight to see if it affected how much light was able

to come through. The first color was blue. The flashlight was placed 1 cm away from it the light probe

on the other side of the color collected the amount of light that came through. This process was

repeated 2 more times an average was then determined. The second color to be used was red. The

light probe on the other side of the color collected the amount of light that came through. This process

was repeated 2 more times and an average was determined. The third color to be tested was silver.

The light probe collected the amount of light that came through and the data was recorded. This

process was then repeated 2more times. Then an average was determined. The last color that was

tested was black. The flashlight was placed 1 cm away from the color and then was turned on. The

light probe collected the amount if light that came through. The data was recorded and an average

was determined.

Different colors of mirrors were tested to see if it affects how much light that reflected. The first color

that was tested was green. The flashlight was placed 5 cm away from the mirror and the light probe

on the other side. The flashlight was turned on and the light probe collected the data. This process

was repeated 2 more times and then an average was determined. The second color that was tested

was blue. The flashlight was placed 5 cm away from the mirror and the light probe on the other side.

The flashlight was turned on and the light probe collected the data. This process was repeated 2

more times and then an average was determined. The third color that was tested was red . The

flashlight was placed 5 cm away from the mirror and the light probe on the other side. The flashlight

was turned on and the light probe collected the data. This process was repeated 2 more times and

then an average was determined. The fourth color that was tested was black. The flashlight was

placed 5 cm away from the mirror and the light probe on the other side. The flashlight was turned on

and the light probe collected the data. This process was repeated 2 more times and then an average

was determined. The last color that was tested was clear. The flashlight was placed 5 cm away from

the mirror and the light probe on the other side. The flashlight was turned on and the light probe

collected the data. This process was repeated 2 more times and then an average was determined.

Different sizes of width of candles were tested to see if it affected the amount of light that the candle

was producing. A 1.75 cm candle was tested first. It was placed on a table and the light probe was

placed 5 cm away from it. The candle was then lit, using matches and the light probe collected the

amount of light that the flashlight produced. This process was repeated 2 more times and then an

average was determined. A 3.5 cm candle was tested second. It was placed on a table and the light

probe was placed 5 cm away from it. The candle was then lit, using matches and the light probe

collected the amount of light that the flashlight produced. This process was repeated 2 more times

and then an average was determined. A 7 cm candle was tested third. It was placed on a table and

the light probe was placed 5 cm away from it. The candle was then lit, using matches and the light

probe collected the amount of light that the flashlight produced. This process was repeated 2 more

times and then an average was determined.

A candle was placed at different distances from a light probe to see if it affected how much light the

light probe collected. The candle was placed 1 cm away from the light probe and then lit using a

match. This process was repeated 2 more times and then an average was determined. Then the

candle was placed 8 cm away from the light probe and then lit using a match. This process was

repeated 2 more times and then an average was determined. After that, the candle was placed 15

cm away from the light probe and then lit using a match. This process was repeated 2 more times

and then an average was determined. Last, the candle was placed 25 cm away from the light probe

and then lit using a match. This process was repeated 2 more times and then an average was

determined.

RESULTS AND DISCUSSION

Figure 3. As shown, the different types of flashlights affect how much light is produced.

It was determined in the first experiment that the type of flashlight used does affect how much light

that is produced. This is because of the wattage of the light bulb inside the flashlight. However, the

wattage does not make a big difference in how long that the light of the flashlight lasts the wattage

should not make a difference in how long a bulb last. However, it will make a bigger difference in how

much light that the flashlight produces. A higher wattage bulb will draw more current and then in

result the flashlight will produce a brighter light. The lower the wattage of the bulb is, the flashlight will

draw less current and this result in dimmer light than the higher wattage bulb. This is why the LED

Technology flashlight produced a brighter light than all the other flashlights because it had a higher

wattage bulb. It can also be concluded that the Husky flashlight had the lowest wattage bulb. This

was concluded because the Husky flashlight produced the dimmest amount compared to all the other

flashlights. The higher the wattage of the bulb the brighter the light it and the lower the wattage of the

bulb is the dimmer the light is.

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Figure 4. As seen, the distance away from the flashlight affects how much light is picked up.

In the second experiment, it was found that the distance away from the flashlight affects the amount

of light that is collected. This is mainly because of the spreading of the light. Whenever the flashlight

is up close to the light probe it collects more light because it does not spread over a wide range.

However, whenever the flashlight is moved farther away from the light probe the amount of light that

the light probe picks up is less. The spreading of the light caused all this. As it was shown in figure 4,

when the flashlight was only 1 cm away from the light probe it collected up to 2650 lux. But, when the

flashlight was moved to 8 cm away it only picked up 1072 lux and then when it was 25 cm away from

the light probe it collected a mere 618 lux. The spreading of the light is what caused all of this. The

closer that the light is to the light probe the more light it collects and picks up and the farther away

from the light probe is the less light is collected this is due to the spreading of the light. Therefore,

from this it was concluded that the closer the flashlight is the more light it produces.

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Figure 5. As is shown, the brand of battery has little effect on how much light the flashlight produced.

In the third experiment, it was found that the brand of the battery has little effect on how much light

the flashlight produces. The flashlight uses the same amount of energy from the battery regardless of

the type of battery. It is only up until the last few minutes or hours that a change in the amount of light

produced would be noticed. This is because the flashlight is using the remaining energy that the

battery has to produce light and the flashlight may have to use less so than the amount of the light

produced would be smaller. However, brand new batteries were used to conduct the experiment so it

had very little effect on the amount of light that it produces. In all, there is no major difference

between the different brands of batteries that were used. All of the batteries stayed around 720 lux

with only a minor spike from Energizer batteries. From this, it was concluded the brand of battery

does not have an effect on the amount of light produced.

Figure 6. As is shown, the amount of time that the flashlight is left on for has little effect on how much light it produced.

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In the fourth experiment, it was found that the amount of time that the flashlight is left on for has little

effect on how much light it produces. Keeping in mind the result from the previous experiment, the

brand of battery does not have an effect on how much light that the flashlight produces. This relates

to the previous experiment because the flashlight will keep using the same amount of energy from the

battery until there is little to no energy left, then the flashlight produces less and less light until the

battery is dead. In this experiment, however, the amount of time was to short to make a difference

because the batteries could still supply the same amount of energy. This was supported because on

10 sec, the flashlight produced around 519.5 lux but then when it was at 500 sec it was still producing

around 430 lux. This a small change of the light that was produced.

Figure 7. As seen, the distance that the flashlight was held from the mirror has effect on how much of the light was reflected.

In the fifth experiment, it was found that the distance away from the mirror/surface had effect on how

much light was reflected. This was because of the spreading of the light as was described in the

second experiment. So the closer the flashlight was held to the surface/mirror the more light the

surface/mirror reflected because more light had hit it in the beginning. In addition, the farther away the

flashlight was held the less light was reflected because of the amount of light that actually hit the

surface/mirror due to the spreading of light. This is because the farther away the flashlight is held the

less amount of light is collected. As a result, when the flashlight when was 1 cm away from the

surface/mirror it reflected around 210 lux and when it was 40 cm away it only reflected around 20 lux.

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Figure 8. As seen, the brand of soap does not have a huge effect on how much light it let through.

In the sixth experiment, it was determined that the brand of soap that is used over the lens of the

flashlight does not cause a huge effect, but that the soap does cause some of the light to be blocked

off. The reason for this is that the soap absorbs the light. Therefore, when the soap absorbs the light

there will be less light coming through. In addition, that the brand of soap does not matter because it

is made up of the similar ingredients. But when there is no soap there is more light produced and

collected because none of it is absorbed as it would have been with soap. This was supported by the

graph because the 3 different brands of soap all collected around 138 lux of light, but when there is

no soap on the flashlight lens there is more light produced. Just because less light is collected does

not mean that the flashlight produces less light because of the soap it simply means that the soap

was what was causing the decrease in light collected because the soap is absorbing the light that

comes.

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Figure 9. As seen, the different colors have effect on how much light that was let through.

In the seventh experiment, it was found that the color that is put up in front of the flashlight does affect

how much light is able to come through. The reason for this was that different colors absorb light

differently. As the graph shows, the color of the plastic wrap does have some effect on how much

light is able to come through. The reason for this is that colors absorb light differently. The graph

shows that the darker the color gets the more light is absorbed and the lighter the color is the less

light was absorbed. Clear plastic wrap let 200 lux of light to go through where black let only about 75

lux through.

Figure 10. As seen, the color of the mirror effects how much of the light was reflected.

In the eighth experiment, it was determined that the color of the mirror had an effect on how much

light was reflected off the mirror. It was also concluded that the black mirror reflected less light than

the clear mirror. This was because the darker the color of the mirror the more light is absorbed

resulting in less light reflecting and vice versa. An example of this would be the difference between

the reflection of the black and the green mirror. When the mirror color was green it reflected about

280 lux, however the black color of the mirror only reflected about 115 lux. This is a huge difference

between the two and is a clear example of why the color of the mirror effects how much light is

reflected. Overall, it was concluded that color clear reflects the most light and color black reflects less

light.

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Figure 11. As shown, the width of the candle effects how much light was produced.

In the ninth experiment, it was determined that the size of the candle has some effect on the amount

of light that the candle produces. The reason for this is the candlewick on the candle. The larger that

the candle was the larger the wick was. The wick is what mainly controls the flame and the amount of

light that candle gives off. Keeping this in mind, the larger the candle got in the experiment the larger

the wick of the candle is. This was supported by the graph because when the candle was 1.5 cm wide

the candle only produced about 36 lux of light and when the candle was 7 cm wide the light that it

was produced was greater being about 46 lux of light produced. The graph shows that the thicker the

candle was the more light was produced.

Figure 12. As seen, the distance away from the candle affects how much light is collected.

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In the tenth, experiment it was determined that the distance away from the candle effects how much

light was collected and the farther away the less light was collected. The same thing applies as to the

other experiments that the spreading of the light has a lot to do about how much light reaches

somewhere at different distances away. The farther away that the light probe was from the candle the

less light was able to pick up. This was mainly due to the spreading of the light, the farther that the

candle goes from the light probe; the less amount of light was collected because the spreading of the

light was bigger. However, if the candle was closer to the light probe, then the amount of light that

was recorded will be larger due to the spreading of light. This was because the light does not spread

out as for because it was more focused one just one object. That was why when the flashlight was at

1 cm the light probe collected about 325 lux but when the candle was 25 cm away from the light

probe the light probe only collected about 17 lux of light. This was all due to the spreading of the light

and the distance which the candle was placed.

CONCLUSION

It was determined that the brand of flashlight affects how much light was produced. If the choice was

between an LED technology flashlight and a Husky the better choice would be the LED Technology

flashlight because it produced the most light compared to all of the other flashlights. The data

recorded supported the hypothesis that was made because the LED Technology flashlight produced

more light than the other flashlights. It could be interesting to see whether the temperature

surrounding the flashlight has effect on how much light the flashlight produces.

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Brain, Marshall. "How Batteries Work.". HowStuffWorks. HowStuffWorks, Inc. 2013. Web. 2/2/2013

“Energy Activities for Teachers and Students.” Energy Information Administration. 11 February 2007. Web.

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Gregersen, Erik. Electricity and Magnetism. New York: Britannica Educational Publishing, 2011. Print.

Lewis, Peter. Light and Sound. Tuscan: Brown Bear Books Limited, 2010. Print.

Parker, Steve. Electricity. New York: DK Publishing, 1992. Print.

"Science." Compton's by Britannica. Encyclopædia Britannica Online School Edition.

Encyclopædia Britannica, Inc., 2013. Web. 15 Feb. 2013.

Zike, Dinah, et al. Electricity and Magnetism. New York: McGraw-Hill Companies Inc, 2002. Print.