How The Length Of A Wire Is Affected By The Resistance
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Introduction To investigate how the length of a wire affects resistance in an electric circuit, different lengths of wire will be placed in an electrical circuit and the effects will be observed. An ammeter and voltmeter will be used to measure the current and voltage in the circuit. Then, resistance will be worked out by dividing the voltage by current. Resistance is the measure of how hard it is for electricity to push through a circuit. All conductors resist the flow of current to some extent. Howeaver, some resist more than others. The...
Overall, the experiment went well as the data fully supported the prediction, with the exception of one outlier (the average of the 50cm wire test). The prediction was based on the theory that the longer the wire, the further the current has to travel which gives a longer amount of time that the current is travelling against the ions creating resistance (as explained in further detail previously in the Introduction). The fact that the data supported the prediction shows that the experiment was carried out well with at least an adequate amount of accuracy as it produced the results expected.

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Aim:- We will investigate... Aim:- We will investigate the length of a wire in a series circuit, and if it will affect its resistance. Prediction:- Resistance is the force of which opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. I predict the resistance will vary with the length. I also predict the longer the wire the less current will flow which increases the resistance. This is because electric current is the movement of electrons through a conductor, so when resistance is high, conductivity is low. Therefore, the electrons will have to push their way through a shorter path of atoms in the wire, reducing their resistance. Whereas, if the length was longer, then the number of atoms in the wire increase. Electrons are negatively charged particles, and protons are positively charged atoms. Electrons move around, but protons don't move, they stay in the same place. Current is a flow of electrons, and is measured in amperes A. When a current flows through a resistance, energy is given off as heat. I think the thicker and shorter the wire, the lower the resistance. I think this because, for example, if you had a road with cars parked to the side and only one car at a time can pass the cars parked on the side of the road as the road is so narrow that allows two cars to go at a time, but as it seems that there are cars parked, that only one car can move past the parked cars; in this case it will be slower for the cars to pass, because the road is long and narrow. Whereas, if the road was wider thinker and shorter it would be quicker. DIAGRAM OF THE THICKNESS AND LENGTH Planning:- Before I do start my investigation I will need to set up my circuit. I will need a variable resistor connected to a power supply, an ammeter and a voltmeter voltmeter parallel to the nichrome wire. I will move the knob on the variable resistor into five different positions for each one length e.g:- 10cm, 20cm, 30cm "¦"¦.. I will get five different readings for each length, and I will be doing five different lengths, which makes twenty-five readings all together, on the voltmeter and ammeter. I will calculate the resistance with this equation:- V = R x I OR Potential difference volts, V = Current amps, A x Resistanceohm, This is how my circuit will look like when I've finished setting it up:- DIAGRAM OF CIRCUIT I will link all the components together with the wire connected to the circuit with crocodile clips at the length of 10cm. I will use to measure the voltage using a voltmeter and recording the results on a table. I will also need to measure the current using an ammeter and recording the results for them too. When I have the results I require, I will use the calculator and divide the voltage by the current to get the resistance. I know that I will need to turn off and on the power supply every time I investigate another length of the wire. This is because the wire intends to warm up and this may have an effect on my other readings and also the wire can snap in half by melting. To keep my investigation fair, I will keep the voltage on the power supply the same, the type of wire and the thickness, and also do the investigation in the same surrounding temperature. Analysing:- I have calculated the resistance of each length on the nichrome wire. I have used these results of values to plot a graph of resistance against length. Length goes along the bottom axis because it is the dependent variable. Its value depends on the length of the wire chosen The points on my graph are a little scattered, none of the points touch the line of best fit, but they are quite close together.. On my graph of the length against gradient, I have rejected one point. I would of rejected two, but I have noticed that the 10cm point was very high, I was going to also reject the 40cm point too, but I was more curious on the 10cm. my table of results suggests that the voltage reading for one point in the 10cm trial was very high compared to the other results of 20cm, 30cm, 40cm and 50cm. but I reckon that I must of miss read the meters whilst investigating. I have noted my working out on the graph of current against voltage. On my graph of current against voltage, there is an anomalies point which I have circled. It is the 10cm point of 0.90V and 0.18A which I must have rejected on the graph of length against gradient. So this is the reason of my rejection on the graph of length against gradient. You can see that this one point has affected the gradient. And as I mentioned that I must of miss read the meters.   

Aim:- We will investigate the length of a wire in a series circuit, and if it will affect its resistance. Prediction:- Resistance is the force of which opposes the flow of an electric current around a circuit so that energy is required to push the charged...

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Aim: To investigate the heat... Aim: To investigate the heat loss of the insulating materials, bubble wrap, cotton wool, blanket and foil Introduction: I will carry out this investigation by measuring the temperature of hot water in beakers insulated with these materials. Naturally the insulated beaker with the warmest water will have prevented the most heat loss. To understand how materials prevent heat loss I need to look at the three ways in which heat can be transferred or lost to the surroundings. One of the ways is conduction. This is when heat energy is transported along an object from the hotter region to the cooler region. The object itself does not move. So when an object is heated, its atoms start vibrating with the heat energy. The free electrons begin to diffuse through the object and collide into other electrons transferring kinetic energy. Substances that have particles close together, like metals are good conductors. Meanwhile gases have particles that further apart so they are poor conductors. Therefore things that are made of particles that are not close together, are poor conductors but good insulators such as gases. Another way is convection, which only happens in liquids and gases. This is when heated particles start moving faster so they move further apart. The heat also makes the particle expand so they become less dense than the unheated particles. As a result of this, the heated particles rise upwards taking the extra energy with them and are replaced by colder and denser regions. A form of convection is in evaporation where the particles in a liquid keep bumping into each other. Sometimes they collide with each other with kinetic energy. During these collisions some particles receive so much energy that they can break away from the liquid. The final way in which heat can be lost is through radiation. This is the transfer of heat energy by waves. Every object sends out infra red radiation but hotter objects send out more. This is completely different to conduction and convection as it does not require particles, so the so infra-red radiation can pass through a vacuum. Also dull and black surfaces emit more heat while shiny and white surfaces emit less. However this makes black and dull surfaces better absorbers Prediction: With the kinetic theory on mind, I predict that out of the materials of foil, bubble wrap, wool and blanket the bubble wrap will be the better insulator. This is because the bubble wrap has a lot of air trapped in its pockets. Air is a very good insulator as its particles are widely spread out therefore there is a less chance of them colliding and passing energy on. This means that there will be less energy transferred to the surroundings, as the bubble wrap would prevent heat loss mainly through conduction. Furthermore the material is made from plastic which in itself is a good insulator. As the aluminium foil is shiny it will reduce heats loss through radiation by reflecting heat back in, like a flask. However since it is a metal, some heat will be lost through conduction. Naturally the blanket material would be a good insulator as its purpose is to keep people warm. This because it has lots of layers and like the wool has air trapped between it fibres. So by reducing heat loss through conduction it should be a good insulator but not as good as the bubble wrap. This is because as it is a dull and black colour some heat will be lost through radiation. The cotton wool is also material that has a lot of trapped air in between its many fibres. Even though it is a good insulator, I feel that because of the thinness of the material the bubble wrap will still be the better insulator. All these materials except the foil are lagging which are insulating materials that have tiny air pockets that trap air to prevent heat from being conducted away. Safety: Since I am dealing with very hot water there are precautions I will need to take. Firstly I will abide to the general laboratory rules i.e. tidy workspace, loose clothing tucked away, and safety goggles. When I need the water for my experiment I will my teacher to pour the hot water. Preliminary investigation: For my investigation I need to know at what intervals I should record a temperature reading and for what period of time. Here are the results of my preliminary investigation: Time Secs Temperature °C 0 84.5 30 80.5 60 77.0 90 75.5 Time Mins Temperature °C 0 84 1 80 2 74 3 72 These results show that taking the temperature readings at 30 second intervals would make the results more accurate and to do this over a 5 minute period. I will also use 80 ml of boiling water and make sure all starting temperatures are the same. Range of results: My results will fit into a table like this, TIME SECS TEMPERATURE OF WATER IN BEAKER ºC CONTROL WOOL BUBBLE FOIL BLANKET Apparatus: In my experiment I will use the following equipments: Electric Kettle "“ To boil the water 5 Beakers "“ To hold the hot water for the experiments Aluminium Foil Bubble Wrap Cotton Wool Blanket Thermometer "“ To measure the temperature Stopwatch "“ To time the experiments Elastic Bands "“ To hold the materials in place Variables: In my experiment the volume of the water for each beaker will be 80 ml. Temperature readings will be taken at 30 second intervals for 5 minutes and I will make sure all beakers have the same starting temperature. Therefore there will 10 readings after the starting temperature. This will ensure my test is fair. The only thing that will be different is the material around the beakers. Method: First of all I will wrap four of the beakers in the materials with the elastic bands. The other beaker will stay uncovered as it is the controlled experiment. After placing the thermometer into the beaker, the 80 ml of water will be poured in and the stopwatch will be started straight away. Also the starting temperature recorded. After that the temperature reading will be recorded at 30 second intervals shown by the stopwatch. This will be done for 5 minutes and repeated for all the beakers. Results: TIME SECS TEMPERATURE OF WATER IN BEAKER ºC CONTROL WOOL BUBBLE FOIL BLANKET 0 83.0 83.5 83.0 83.5 83.5 30 80.5 80.0 81.5 79.5 80.5 60 77.0 78.0 80.0 77.5 78.5 90 75.0 76.0 78.5 76.0 76.5 120 73.5 74.5 76.5 74.0 75.5 150 72.0 73.5 75.5 73.5 74.5 180 70.0 72.5 74.5 72.5 73.5 210 69.0 71.5 74.0 71.5 72.5 240 68.0 70.5 73.0 70.5 71.5 270 66.5 70.0 72.5 69.5 71.0 300 65.5 69.5 72.0 68.5 70.5 Observations: For all the materials there is a sharp drop in temperature for the first minute and after that it gradually slows down. The starting temperatures for the insulated beakers are very close but at 5 minutes they the end readings are more spread out. As you can see on the graph the bubble wrap has the most gradual curve and consequently the slowest rate of heat loss. From the starting temperature of 83.0 °C, it dropped by 12.0 °C after 5 minutes. The blanket is the second best insulator with the temperature drop of 13 °C from a starting temperature of 83.5 °C. The cotton wool lost 14.0 °C from a starting temperature of 83.5°C The aluminium foil is the worst insulator from the materials as from a starting temperature of 83.5 °C it lost 15 °C The controlled experiment the beaker with no insulation has the steepest curve and therefore the fastest heat loss. From the starting temperature of 83.0 °C, it lost 17.5 °C after 5 minutes. Conclusion My prediction was correct as the bubble wrap material was the best insulator because it prevented the most heat loss being the best insulator. The bubble wrap was the best insulator due to its ability to reduce heat loss through conduction. This can be understood by looking behind theory of conduction. Since heat is energy associated with the motions of the particles making up a substance, it is transferred by these motions, shifting from regions of temperature, where particles are more energetic to regions of lower temperature. The rate of heat flow between the two regions is relative to the temperature difference and the heat conductivity of the substance. In solids the molecules are bound and add to the conduction of heat mainly by vibrating against neighboring molecules. However a more important mechanism is the migration of free electrons. Materials such as metals have a high free-electron density therefore they are good conductors of heat while non-metals do not conduct as well. Since gases and liquids have their molecules even further apart they are generally, very poor conductors which makes them good insulators. Therefore the bubble wrap which is made up of lots of air pockets has not only less free electrons to transfer heat but it has molecules the trapped air that are quite far apart. This makes harder for heat from the boiling water in the beaker to be conducted away through the bubble wrap and to the surroundings The blanket and cotton wool were also quite good insulators as they too have a lot of air trapped between the fibres. The foil was not as good because being a metal it had more free electrons with particles being closer together, for heat to be conducted away to other regions. However, since it was quite shiny it reflected some heat back in, to the beakers, such as the effect of a flask so it prevented heat loss better than the controlled beaker. The controlled beaker naturally let out the most heat since it had no form of insulation except the fact that it the beaker was made out of glass which in itself is a fairly good insulator. Evaluation The method that I used to carry out my investigation was fairy simple to carry out. It required me to pour out 80 mls of hot water into beakers insulated with different materials. The temperature of the water was then recorded over a 5 minute period at 30 second intervals. The results of my investigation were accurate as I took my readings at eye-level to the nearest half a degree centigrade. I had no anomalous results and the accuracy can be seen on my results graph where the readings are close to the best fit curve. However I could have been even more accurate as if the time h d been available tome, I would have repeated my experiments to get an average of the results. Another way in which I could have improved my experiment was if was available to me, I would have used a data logger with temperature probe. This would have given me very accurate readings every second. I could have also used polystyrene lids to reduce heat loss by convection in the beakers. To extend by investigation I could have used different beakers like copper cans to see how the material of the beaker affects the rate of heat loss. In addition I could look at the effect of the amount of layers of material insulating the beaker as well as looking at different volumes of boiling water.   

Aim: To investigate the heat loss of the insulating materials, bubble wrap, cotton wool, blanket and foil Introduction: I will carry out this investigation by measuring the temperature of hot water in beakers insulated with these materials. Naturally the insulated beaker with the warmest water will have prevented...

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The aim of this experiment is...The aim of this experiment is to find out if the resistance of a piece of wire will change if we vary the length. To do this I will set up a circuit that will include an ammeter, a voltmeter and a piece of wire. The wire will be a different length each time. I think that there will be more resistance on a longer piece of wire "“ the longer the wire, the higher the resistance. This will happen because of the amount of particles inside the wire that the flow of electrons will need to pass. In turn, there will be more collisions between the electrons and the atoms inside the wire. This is the resistance. A higher resistance will mean more collisions. To succeed, I will need to keep the temperature below a certain level as if the wire gets too hot, the atoms inside the wire will begin to move more and this would affect the resistance. I also need to be sure to use the same thickness and type of wire each time. If the wire was thicker on one measurement, there will be more atoms that the negative electrons would collide with. The wire I will use is Constantine 0.31mm wire. My preliminary work shows which voltages to use without the wire getting hot. Length cm Voltage V 10 0.25 20 0.35 30 0.42 40 0.71 50 0.96 60 1 These voltages prevent the wire from heating up, so all I need to do is keep the voltage below 1V each time. I need to keep all of these the same to be sure of obtaining a reliable set of results, and a fair test. I am deliberately changing the length of the wire and the voltage to prevent the wire from heating. I decided to use six different values, from 10-60cm long wires. I think this is better as the difference between the highest and lowest is high. If the values had smaller differences, a mistake of 1mm in the measurement could make a huge difference, but it would not make as much difference in the values I am using. To make sure the results are reliable, I will repeat the experiment and work out an average between the two results I have. This is in case of an inaccurate result. Length cm Current A Voltage V Resistance ? Average ? 1 2 1 2 10 0.37 0.33 0.25 0.694 0.714 0.704 20 0.26 0.26 0.35 1.346 1.346 1.346 30 0.22 0.22 0.42 1.909 1.909 1.909 40 0.28 0.28 0.71 2.536 2.536 2.536 50 0.3 0.3 0.96 3.2 3.2 3.2 60 0.26 0.27 1 3.846 3.704 3.775 First of all, the resistance did increase as we increased the length of the wire. The results are almost on a straight line, so it seems that the resistance is directly proportional to the length of the wire. If the length is doubled, the resistance also doubles. The line of best fit does not go through the origin. It would be thought that no wire would have no resistance, but the crocodile clips and the connections would also have a resistance. Every point lies almost exactly on the line of best fit, except the 30cm measurement, although it is only around 0.5? from it. My original hypothesis was correct "“ the resistance increased with the length of the wire. This happened because of the amount of particles inside the wire that the flow of electrons will need to pass. In turn, there will be more collisions between the electrons and the atoms inside the wire. This is the resistance, and a higher resistance will mean more collisions between the free electrons in the current and the atoms inside the Constantine wire. The results are accurate, as I used very small measurements cm/mm and left my results at two decimal places. If I had, for instance, used inches and rounded all of the results to one or no decimal places, the results would be far less precise. I can also tell that they are reliable as the graph makes an almost exact straight line. Had the results been all over the graph with a line of best fit far away from the points, I could not say this. I am very confident that my conclusion is right. This is because of the fact that the points lie on a straight line that is directly proportional to the y-axis. If the length is doubled, the resistance also doubles. To improve the reliability, I could repeat the experiment more than just once. If I had an average of three or four tests, I would have a far more accurate graph. Resistance is measured in ohms.   

The aim of this experiment is to find out if the resistance of a piece of wire will change if we vary the length. To do this I will set up a circuit that will include an ammeter, a voltmeter and a piece of wire. The wire will be a...

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I plan to see... I plan to see if the body size of an animal affects its heat loss. I am going to do this by using three glass beakers with various amounts of boiling water in them. I will then see which beaker looses its heat the fastest or the slowest. Prediction I predict that the smaller the animal the faster that it will loose its body heat so I predict the smaller beaker will loose its heat the fastest and the largest one will loose its heat the slowest. The science I predict this because for example if you have a drop of boiling water and a jug of boiling water the drop of boiling water will cool down the quickest. I have also predicted this because the wild animals in the cold adapt to their environment by the size of their bodies and shape. I will be focusing on the size. E.g. polar bears live in cold weather so they are big to reduce heat loss. Apparatus "¢ 3 glass beakers "¢ kettle "¢ thermometer "¢ 3 timers Safe test I will make sure that my experiment is safe by "“ "¢ Making sure that I handle the boiling water carefully. "¢ Making sure that the water doesn't spill near any electricity or on the floor "¢ Make sure that I do not smash anything Fair test I will make sure that my experiment is fair by "“ "¢ Having the water at the same temperature at the start of the experiment. "¢ Don't not insulate them "¢ Do the same to each one. E.g. if I stir one I will have to stir the others. Range and extent "¢ 20 minutes timing "¢ Beakers "“ 100ml, 200ml, 300,ml Variables There will be 100ml in one beaker, 200ml in another and 300ml in another. This will not affect my investigation because these variables are significant to my experiment. Method Firstly I will set up my equipment data logger, water and computer. The beakers will be set out with the right amount in each one and the temperature readers will be placed in each beaker. And then I will press start on the computer and the data loggers will record my results on a graph and also on a table so I can spot exactly where any anomalies occur. This will be done for 20 minutes and when it is finished reading I will print out the required information that I need. Conclusion From doing this experiment have found out that the smaller the animal the quicker that it looses its heat and the larger the animal the slower it looses its heat. My prediction was proved correct. The water temperatures started near enough at the same temperature and they have all dropped in Celsius but the 100ml dropped even more. Here I how they dropped: Start Finish Range 100ml 89.4 52.5 39.9 200ml 91.2 59.2 32 300ml 91.2 61.9 29.9 In the table you can clearly see how my prediction was correct however I would have expected more of a difference between the 200ml and the 300ml. The bigger the animal the slower it looses its heat and the smaller the animal the quicker it looses its heat. Animals in colder conditions are mostly large because the condition they live in is cold. If you look at the graph you can see how my results dropped. Evaluation I don't think that my experiment was very successful even though my prediction was correct. I don't think it was very successful because of the actual experiment. Here are my reasons: "¢ The 100ml beaker didn't start off at the same temperature of the other two. "¢ There are two anomalies in my results where the temperature had dropped dramatically I think that this has happened because maybe the temperature reader came out of the water for a few seconds. That is the only explanation that it could possibly be. Apart from the anomalies, my results do support my conclusion. If I was to repeat this investigation then I would stick the data loggers down to the beaker so that they do not come out of the water. I would also repeat the experiment 3 times to be more accurate and I would also include a 400ml and a 50ml amount in the experiment. By doing this I would have found out more information and made my results more accurate. If I had more time then I would research the sizes of animals in different climates. This will have made me surer about my conclusion.   

I plan to see if the body size of an animal affects its heat loss. I am going to do this by using three glass beakers with various amounts of boiling water in them. I will then see which beaker looses its heat the fastest or the slowest....

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