As a part of this tasks, I will conduct a survey to show the way in which light is produced in the following types of lights;-* Domestic* Industrial/commercial* OutdoorDomesticFor the domestic lights, I have used house hold light bulbs which are made from a tungsten wire. the tungsten wire is placed inside a glass so that when it is heated, it does not react with oxygen to produce a oxide. The diagram below shows a tungsten light bulb.
the voltage that is passed though the power supply goes to the tungsten wire and interferes with the atomic structure of the electrons on the atom of the tungsten. this is because the voltage is energy, and this energy moves the electrons for the orbital of the nucleus of the atom. If one of the electrons in the shells of the atom move out of place, then this must be replaced by another one straight away to keep the orbital of the electrons around the nucleus right.
So to do this, one of the electrons from the outer shell of the atom jumps in to the place of the atom that was knocked out by the voltage. In doing so, a photon of energy is passed out. This photon is the light we see when we turn on a bulb.The tungsten metal is a good metal to be used for this kind of job. This is because tungsten has a high atomic number. This means that there are more shells of electrons. More electrons would mean that more photons can be produced from this metal which make it idle and give it a high melting point.The tungsten has to be placed in a glass container.
This is to stop oxygen coming in to the bulb and reacting with the tungsten. the glass is filled with a noble gas like argon. This is because argon does not react.The process by which the tungsten bulb produces light is called incandescence.Advantages and disadvantages of using a tungsten light bulbAdvantagesdisadvantageThe tungsten light does not cost a lot to make and it has a very simple structure.
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The glass that is used to cover the bulb can easily break and cause harm to people.The tungsten metal wire that is used is a good conductor, which allow is to get very bright with a small piece of wire.The tungsten can get used up as all the electrons start to run out of the atoms. This means that the bulbs stops working.The glass that is used to cover the tungsten precedes protection for the heating of the tungsten with gets hotter then 2400oC.The light can take some time to brighten up as the tungsten takes a bit of time to warm up.The light that is produced form the light bulb allows as to see when it is dark.
The tungsten wire is very sensitive and if the bulb is drop or shaken, the tungsten wire can brake of ripe which stop the bulb from working.The light bulb is easy to fit onto the socket. So this means that it can be change by an untrained person.The light bulb gets very hot after it has been used. If a person touches it, then it will burn them.
They can be used to produce all different coloured light by placing different filters.The life time of the bulb is reduced by constant use of the bulbIndustrial/commercialThe halogen light bulb is used in industries to light up the areas of work. The reason for using halogen light in the place of work is because they have a longer life. This is important because in industries, lights are always on.Below, I have drawn a diagram of a halogen lamp.With normal tungsten lights, they are filled with noble gases.
This is so that the tungsten does not react with the gas that in the glass container. With normal light, when the tungsten wire gets hot, some of its particles of the evaporate from the wire and stick to the side of the glass that holds the wire. This makes the glass cloudier and allows less light to get though. This means that with time, the amount of light transmitted by the light bulb is reduced. This is called lumen maintenance.
With halogen light bulbs, the gas that is in the bulb is different from the normal light bulbs. Mostly halogen light bulbs contain iodine of bromine. When the tungsten evaporates from the surface at high temperatures, it combines with the halogen gases. For the tungsten to stay combined with the halogen gases, the temperature of the surrounding must be 200OC. this stops the tungsten partials from condensing on the glass in with the tungsten is contained, which stops it from the glass getting cloudier. This means that the light intensity always stays the same in a halogen light unlike a normal light bulb.With normal light bulbs, the particles of tungsten evaporate from the surface of the wire and stick to the glass side.
This means that the overall amount of particles on the wire reduces. This reduces the lifetime of normal light bulbs as it comes to a point where there is too less particle of tungsten left on the wire for it to produce light.With a halogen light, this does not happen. This is because when the temperature of the surrounding of the bulb of a halogen light drops below 200OC, all the tungsten and halogen compounds are come unstable.
So when this happens, the particles of tungsten separate from the halogen gas and go and stick back to the tungsten wire. This means that less tungsten particles are lost to the surrounding which gives it a longer lifetime.The shape of the container that the bulb is in is different. This is more like a tube. This is so that the halogen gases are always near the tungsten wire. This allows all the particles to react with the halogens faster and to be disposed back on to the wire faster.To stop the surrounding of the light bulb to rise in temperature, the halogen light bulb is contained in a stronger glass like quartz.
This is because it is harder to heat up stronger glass and also it doesn’t brake easily.Advantages and disadvantages of using a tungsten light bulbAdvantagesDisadvantageThey have 5 times longer lifetime then normal light bulbs. This means that they need to be changed less often and money is saved.
Halogen light bulbs operate at higher temperatures then normal light bulbs. This means that there is a bigger risk of getting burns from the bulb.The light intensity is always kept constant, as the glass does not get cloudier.Halogen light bulbs can brake or even explode as they are made from glass. If the glass is hot, it can start a fire.A halogen light is brighter then normal light bulbs.
If shielding brakes, then it exposes ultraviolet light to surrounding.Gives very good colour rendering as it produces a whit light.. They cost more then normal light bulbsHalogen light bulbs provide full light intensity when it is turned on.
It does not need time to warm up.Halogen light bulbs above the power of 300 Watts have a higher risk of starting a fire. For this reason, they are not allowed for dormitory usesOutdoorSolar yard light are used in the outdoors. This is because the energy is made and stored from then sun and then it is used when it is dark.Below is a diagram of a solar yard light.The solar yard lamp consists of the following things:-* A case made from plastic* Solar panel on top made from solar cells* A single AA NiCad battery* A controller board* An LED light source* A normal tungsten light bulbThe solar panel is formed from many different solar cell. Each cell produce 0.
45 Volts of energy when the light hits it. The amount of current in the solar cell depends on the size of the cell and the amount of light that hits the cell. If lots of cells are put together, then this produces a bigger amount of energy. This is why the solar panel has cell in series to each other.The solar panels are connected to the battery. This battery is charged by the solar panels at daytime. The battery can reach a maximum charge of about 700 milliamp hours and produces 1.2 volts of power.
The LED turns the light on and off depending on the brightness of the day. If it becomes dark (night), then the LED turns the light on by allowing the stored power from the battery to be used for the light. And when it become bright (daytime) the led turns the light off day stopping the power supply from the battery to the light bulb.This way that the bulb produces the light is the same to the way a normal tungsten light bulb works. The only difference is that this time the power supply is coming form the sun (solar power)The reason why this lamp is best for outdoor use is because most of the sun light will hit the solar panel out side the house. This means that this light cannot be used indoors.Advantages and disadvantages of using a tungsten light bulbAdvantagesDisadvantageThe good thing about a solar powered produced is that there is no electric used as the power is supplied by the sun. This means that there is no bill.
They cost a lot to buy compared to other electric powered light bulbs.There is no wires that are needed for the light. This makes it less fiddly.
The light can only be used in a place where the sun will reach it as it will not charge if the sun does not hit the solar panelThe light atomically turns off and on. This means that when the light is needed, it is there with out having to turn it on.The light will not work as will in short days like in winter. This is because the solar panels will not get enough light to charge.
It makes the out side of your house bright and makes it look nice.The solar panels are sanative, they can brake.Task 2As apart of this task, I will be seeing the different colours of the electromagnetic spectrum that is produced from the following domestic light sources:-* Hot filament bulb* Fluorescent tubes* Energy saving filament (ESF) bulbI will compare these light sources with the natural light spectrum.When doing this experiment, I used a hand held spectroscope and tested different sources of light. The table below shows the different colours that where visible in the spectrum with the different light source.ResultsLight sourceSpectra coloursNatural lightROY G BIVSun lightROY G BIVCandleROY G B VEnergy efficientROY G B VFluorescentRO G B VHot FilamentOY G B VMercuryO G VRed lightRSodiumYFluorescent compared with natural lightWhen looking at the colours of the spectrum of fluorescent light, I can see that the colours are very similar apart from the colour indigo and yellow which was missing in the fluorescent light. This must mast mean that the colours was absorbed by the fluorescent atoms.Energy saving filament (ESF) bulb compared with natural lightThis was the same as the fluorescent light source.
This is because the colour indigo could not be seen but, this light also had the colour yellow, which the fluorescent light didn’t have.Hot filament compared with natural lightThis spectrum had the colours red, and indigo missing when compared with the natural light.TASK 3As a part of this task, I will be using a spectrometer and a diffraction grating to work out the wavelength of a sodium lamp light. Below is a diagram of a spectrometer.The diffraction grating has many slits in it. this could be as many as 10,000 per cm. when a light source is passed through the diffraction grating, a pattern of interference fringes is seen on the other side of the grating. When a monochromatic light (single wavelength) light is passed through the grating at 90o form the grating, on the other side of the grating, a interference fringes are formed.
This has been shown in the diagram below.Measurements that need to be taken to work out the wavelength of the waveThe formula below is the general formula that can be rearranged to work out the wavelength of the light.Order of angular separation x wavelength (?) = distance between slits (d) x angle(sin ?)The formula can be rearranged to work out the wavelength of the light that passes through the diffraction grating. This has been shown below.
Wavelength(?) =distance between slits (d) x angle(sin ?)Order of angular separation (n)? = d sin ?nfrom looking at this formula, I can see that I would need to take the following readings to be able to work out the wavelength of the sodium light.* Distance between the slits on the diffraction grating. This depends on the grating that is used.* The angle at which the telescope is placed for the grating. This is found by looking a the venire scale.
* Order of the angular separation of the interference fringes. This is found by observation.Working out the wavelength of a sodium light source.For this experiment, I used a diffraction grating which had 1092 slits per centimetre. To work out the distance between each slot, I must divide 0.
01m by 1092 as the value for d must be in metres . this Has been done below.Value for d (distance between slits)0.01 .1092Order of the angular separation (n) and angle (sin ?)Is was worked out by moving the telescope to the first of the interference fringes for zero angle. This meant that the order I used was 1 which was the value for n.
and then to work out the angle of 1 order, I looked at the venire scale, which read 28o. this means that the value For sin ? which is sin 28o.Using all three of these values, I can work out the wavelength for a sodium light. This has been worked out below.
Wavelength (?) = 9.16 x 10-6m x sin 28o1wavelength of a sodium light = 4.3 x 10-6 m = 430 nm.Task 4 – planningas a part of the plan, I will be planning a series of experiment to measure the light out put of different powered lights using a Lux meter and a LDR. A the end of the plan, I will decide the best method to use for this experiment and make any modifactions if needed.Below I have listed the equipment I will be using.* 5 different light bulbs with different voltages* A power pack and some leads* Small table lamp* A black tube with two wires coming out of it (at the back)* A bulb holder* 2 x Clamp and stand* 2 one metre rulers* Lux meter* LDRBelow, I have listed the different powered lights I will be usingLight bulbs (Coloured)Voltage(v)Current (amps)Power (V x amps)= (w)Royal blue2.
50.20.5Red3.5310.5Orange60.63.6White6.
5319.5Green122.226.4with the five different bulbs, I will be comparing the different light intensity from different distance. I have chosen these five bulbs as they all have more of a different power out put.
This will make it easier for me to plot a graph.Below is a table to show the different kind of reading I will be taking using both the LDR and the Lux meter and the different distance I will be taking it from.The bulb I will use and the power out putDistance (cm)Light intensity (Lux)Light resistance (ohms)20406080100The diagram and the description below shows the two different methods I used for the trailing experiment.
LDR experimentIn this method, I had a LDR which was in a black tube to stop all other light apart from the bulb. The light bulb was placed on a ruler at the point of 0 cm. then the tube holding the LDR was brought to the different distances from the light. And the reading of the resistant was taken down.Lux meter experimentFor this method, I used a Lux meter and held if from different lengths from the light bulb. This didn’t have any tube blocking unwanted light from getting to it.
Chosen methodI have decide that the both the methods above are the best methods to use. This is because they would give the best accurate results. I have made a modification to asks the teacher to close the blinds to stops any other light from interfiling with the accuracy of the results.Time scaleBelow I have planned a 8 week time scale.Week numberTask planned to doLesson 1I will use this week to plan what I will do for the rest of the 7 weeks and how I plan to do it.Lesson 2In this week, I will carry out research on the different use of light source (task 1). Then I will start to write it up.Lesson 3In this lesson, I will carry start on task 2 and use a spectroscope to find the different colours produced by different light sources.
I will then start to write it up.Lesson 4In this lesson, I will start the experiment that I would need to do for task 3. this would be to work out the wave length for a sodium lamp using a diffraction grating.Lesson 5In this lesson I will be trailing the experiment I will being for task 4. at the end of the trailing, I will choose a method for the real experiment.Lesson 6In this lesson, I will start my task 4 and do the real experiment. I plan to do at least 3 different reading for this lessonLesson 7In this lesson, I plan to do another 3 readings and then start my repetitions.Lesson 8In this lesson, I will finish of all my repetition and then start to write up my experiment.
PredictionI am expecting the results to be something like the graph I have shown below for all the results.Task 4 – write upBelow I have shown the result for the experiment. I have presented the tables for each bulbs separately.Results : Royal blue 0.5 watts powerDistance (cm)Light intensity (Lux)Light resistance (ohms)030200.75160110501.
715202.620103.42504.53005.
8Graph: for 0.5 watts bulb (Lux against ohms)Results : Royal blue 10.5 watts powerDistance (cm)Light intensity (Lux)Light resistance (ohms)033200.451800.810601.41530220202.825103.
63004.6Graph: for 10.5 watts bulb (Lux against ohms)Results : Orange 6 wattsDistance (cm)Light intensity (Lux)Light resistance (ohms)0416252902.7101104.815507.6204011253015.6302020Graph: for orange 6 wattsResults for white 6.5 wattsDistance (cm)Light intensity (Lux)Light resistance (ohms)047200.
453600.7101201.115501.720302.
42510330103.8Graph for white 6.5 wattsResults for green 12 wattsDistance (cm)Light intensity (Lux)Light resistance (ohms)040600.752700.810801.815402.
520202.725103.63004.
4Graph for green 12 wattsTask 5as a part of this task, I have decided to discuss the uses of a fluorescent light tube. The diagram below shows how it looks.The way that this light tube works has been explained below.Electrons from the cathode are transmitted into the tube. In side the tube is mercury vapour and argon gas. When the electrons hit the mercury vapour, the vapour turns into gas. This happens because the electron from the cathode hits the electrons in the mercury vapour bond and which brakes the bond and in doing so, it releases a photon of energy.
This photon is the visible light that is produced when a light bulb is turned on.A fluorescent light tube is used in many stores. The reason it is used is mainly because it has a higher range of different coloured wave lengths in the spectrum that is produces. This has been shown in task 2. in task 2, I can see that a fluorescent light tube produces the following colours in the spectrum:-* Red* Orange* Green* Blue* VioletWhen this is compared with a tungsten light bulb, which produces:-* Orange* Yellow* Green* Blue* VioletWe can see that fluorescent light tube produces more colours.This is very important in stores. For example, if a fluorescent light tube was not used in a clothes shop, then the colour of all the clothes would not be able to be seen properly. This would have meant that customers would think that the colour of the clothes is different to what it really is.
by using a fluorescent light tube in stores, it has made the customers see the true colours of the produces they are about to buy. This make the fluorescent light tube good for its purpose.The fluorescent light tube is shaped in a long tube (shown in the last page) and when it is placed in a sop floor, it is in parallel with other fluorescent light tubes.
This has been shown in the diagram below. .In task 4, I have seen that the light intensity decreases with the distances. Because the tube is long, this increases the surface area of the light out put.
this means that the light covers a bigger are. This means that there is a less of a chance of light intensity dropping in some parts of the area that the light covers because the light covers a bigger area.AdvantageDisadvantageThey give out 99% of their light to their surroundings and they lose the other 1% as heat.When you switch on the lights, they take couple of seconds before they actually become fully brightThe cost of running this light bulb is a lot less then any other light bulb.The glass tube that the light is produced from is very fragile. This means that it can brake easily.They are long so it provides more light. This is because it has a more mercury in the bulb, which means more light.
As you get more far from the light source, the light intensity drops. This means it is header to see.It has a bigger range of colours in the spectrum it produces.
This allows different colours to be seen.It can be blinding at high powers.It has a very long life time of 10,000 hours.Fluorescent lightsElectrons from the cathode are transmitted into the tube. In side the tube is mercury vapour and argon gas.
When the electrons hit the mercury vapour, the vapour turns into gas. This happens because the electron from the cathode hits the electrons in the mercury vapour bond and which brakes the bond and in doing so, it releases a photon of energy. This photon is the visible light that is produced when a light bulb is turned on.Advantages:They give out 99% of their light to their surroundings and they lose the other 1% as heat.The cost of running this light bulb is a lot less then any other light bulb.They are long so it provides more light. This is because it has a more mercury in the bulb, which means more light.
It has a bigger range of colours in the spectrum it produces. This allows different colours to be seen.It has a very long life time of 10,000 hours.
Disadvantage:When you switch on the lights, they take couple of seconds before they actually become fully brightThe glass tube that the light is produced from is very fragile. This means that it can brake easily.As you get more far from the light source, the light intensity drops. This means it is header to see.It can be blinding at high powers.Street lightsStreet lights work in the same way as a fluorescent light but the only difference is that streetlights contain a sodium spectrum instead of mercury.
This reduces light pollution. They also use reflectors to shine light in the same direction.Advantages:Helps brighten up the street at night so cars and people can go out and about.Disadvantage:Everything is more yellow and dim. Not like sun light.Filament light bulbThere are many different shapes and sizes of Incandescent lamps.
They also have a number of different fittings. The colour of the glass can be changed to produce a different coloured light.The light bulb has a tungsten filament inside it with an argon gas. The movement of the electrons in the atom of the tungsten produced the light that is visible.
The argon all gas stops the tungsten from reacting with the tungsten.The are many different uses for this light bulb. The mean one being the fact that it can be used to see in the dark.Advantages :-The tungsten light does not cost a lot to make and it has a very simple structure.The tungsten metal wire that is used is a good conductor, which allow is to get very bright with a small piece of wireThe glass that is used to cover the tungsten precedes protection for the heating of the tungsten with gets hotter then 2400oC.
The light that is produced form the light bulb allows as to see when it is dark.The light bulb is easy to fit onto the socket. So this means that it can be change by an untrained person.They can be used to produce all different coloured light by placing different filters.
Disadvantage:-The glass that is used to cover the bulb can easily break and cause harm to people.The tungsten can get used up as all the electrons start to run out of the atoms. This means that the bulbs stops working.
The light can take some time to brighten up as the tungsten takes a bit of time to warm up.The tungsten wire is very sensitive and if the bulb is drop or shaken, the tungsten wire can brake of ripe which stop the bulb from workingThe tungsten wire is very sensitive and if the bulb is drop or shaken, the tungsten wire can brake of ripe which stop the bulb from working.The light bulb gets very hot after it has been used.
If a person touches it, then it will burn them.The life time of the bulb is reduced by constant use of the bulbhalogen light bulbsWith halogen light bulbs, the gas that is in the bulb is different from the normal light bulbs. Mostly halogen light bulbs contain iodine of bromine. When the tungsten evaporates from the surface at high temperatures, it combines with the halogen gases. For the tungsten to stay combined with the halogen gases, the temperature of the surrounding must be 200OC. this stops the tungsten partials from condensing on the glass in with the tungsten is contained, which stops it from the glass getting cloudier.
This means that the light intensity always stays the same in a halogen light unlike a normal light bulb.Halogen light bulbs also have a wider rage of colours in the spectrum.Advantages:-They have 5 times longer lifetime then normal light bulbs. This means that they need to be changed less often and money is saved.
The light intensity is always kept constant, as the glass does not get cloudier.A halogen light is brighter then normal light bulbs.Gives very good colour rendering as it produces a whit light.
Halogen light bulbs provide full light intensity when it is turned on. It does not need time to warm up.Disadvantages :-Halogen light bulbs operate at higher temperatures then normal light bulbs. This means that there is a bigger risk of getting burns from the bulbHalogen light bulbs can brake or even explode as they are made from glass. If the glass is hot, it can start a fire.If shielding brakes, then it exposes ultraviolet light to surrounding.They cost more then normal light bulbsHalogen light bulbs above the power of 300 Watts have a higher risk of starting a fire.
For this reason, they are not allowed for dormitory usessolar yard lampA solar yard lamp uses a solar panel to charge the battery at day time and then at night time, the charged battery is used to power a tungsten light bulb.AdvantageThe good thing about a solar powered produced is that there is no electric used as the power is supplied by the sun. This means that there is no bill.There is no wires that are needed for the light. This makes it less fiddly.The light atomically turns off and on. This means that when the light is needed, it is there with out having to turn it on.It makes the out side of your house bright and makes it look nice.
DisadvantageThey cost a lot to buy compared to other electric powered light bulbs.The light can only be used in a place where the sun will reach it as it will not charge if the sun does not hit the solar panelThe light will not work as will in short days like in winter. This is because the solar panels will not get enough light to charge.The solar panels are sanative, they can brake.
