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GCSE: Electricity and Magnetism
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* Battery- to give me a source of power. * Meter stick- to place my wire on, for safety as well. * Ruler- To measure the length of the wire I am going to use To change the resistance for my experiment I will need to change the length of the wire. If I increase the length of the wire the resistance will increase and if I shorten the length of the wire the resistance will decrease. Apart from the resistance I am also measuring for the current and the voltage.
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However, a single -OH group, has replaced one of these outer hydrogen atoms. Strong covalent bonds connect the various atoms to each other although the forces between the alcohol particles are quite weak. This signifies that they have low melting and boiling points and can be easily separated from one another. Here is the structure of ethanol: Alcohols form their own distinct homologous series with these properties: solubility in water (smaller molecules can dissolve in water because of the OH group), higher boiling point than the alkanes (even though the weak intermolecular bonds mean that alcohol should have a very low boiling point, the addition of the OH group allows a higher one)
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The wire will not be interfered with once it has been fastened in place (except to move the clips). I will take 19 measurements. Each observation will convey the volts (pd) across the length of wire (L) measuring from 10 to 200cm. These readings will be taken when the ammeter shows a reading of 0.1 amps (I). The variable resistor will be used to make sure the current stays at 0.1A. EXPERIMENT Apparatus: * 200cm length of 28 Nichrome wire * Power pack * Leads * Crocodile clips * Variable resistor * Voltmeter * Ammeter * 1m ruler (x 2)
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The current flowing into the bulb is the same as the current flowing out of it. In a parallel circuit the same rule applies, current is not 'lost'. It is only a flow of charges travelling slowly around the circuit, rather like water flowing through connected pipes. Current and Charge All materials are made up of atoms, and all atoms are made up of charges. The number of charged particles needed to make a current flow in 1 amp is; 6.2 x 10 charged electrons need to flow in 1 sec, so this is called 1 coulomb.
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I then put the thermometer in the water and added more ice until the water temperature reached zero. Then I put the thermistor in the water and waited until the ammeter reading was constant, and then adjusted the resistance using the variable resistor until the ammeter read nought. Then I recorded the resistance at that point. I did this once for each temperature. I decided that a reading every ten degrees was the optimum range, as this would give me a good set of results, without having too much information which I would not need to use. Diagram of experiment: Method of experiment: I used the same basic method as the preliminary experiment, with the following alterations: I did three repeats to find an accurate average result, which will enable me to plot graphs showing different factors.
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To find out how the length of a piece of nicrome wire Can affect the resistance of electricity in a current.
I Will do this again another 4 times Reducing the length of the wire by 15each time by moving the crocodile clips along. I will do this three times. For all of the sets of results I will divide the volts by the amps to work out the resistance(ohms). I will plot all of these results on a graph along with the average of all the results. The reason for getting three sets of results is that it makes your results much more accurate.
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The sun's heat drives the winds, whose energy is captured with wind turbines. Sunlight also causes plants to grow, and the organic matter that makes up those plants is known as biomass. Biomass can be used to produce electricity, transportation fuels, or chemicals. The use of biomass for any of these purposes is called bioenergy. But not all renewable energy resources come from the sun.
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and in correct places * Throughout the experiment, use wire that is made of the same metal and make sure that you always use metal that has the same diameter to keep it a fair test * Starting with a length of wire that is 10 cm long, connect this with crocodile clips at
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This causes more collisions between the electrons and the atoms as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance. 2.Material: The type of material will affect the amount of free electrons which are able to flow through the wire. The number of electrons depends on the amount of electrons in the outer energy shell of the atoms , so if there are more or larger atoms then there must be more electrons available.
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Temperature - To transfer the energy from atom to atom the electrons move from atom to atom. If the temperature is increased then the atoms will vibrate faster and it is more difficult for the electrons to move from one atom to another, that means conduction decreases and resistance increases. Cross sectional area - If the wire is wider then there is going to be more electrons per mm which means there is more 'charge carriers' per mm therefore meaning that it will conduct better. If the wire is conducting better then therefore the resistance must be decreasing.
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I will do the same for the 80cm, 70cm and so on, until I have reached 0cm. I have decided to use wire at 10cm intervals because it gives a nice even spread over the 100cm range, and it is small enough for me to see where anomalies are. So this means that if anything goes wrong, I can easily see it. I will repeat the experiment three times to make sure that none of my results are way off the mark. If I find that there is an anomaly somewhere in my results I can identify it easily and redo that part of the experiment.
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Accurate resistors can be made from metal wires. Two different types are carbon resistors and wire-wound resistors. Wires can be made from Manganin, Constantan and Nickrome. Ohms' law: Some objects have a high resistance to the passage of electricity through them, and others have a low resistance. The resistance of any object is fixed but it is difficult to measure directly. The resistance of an object is found by measuring the current flowing through it when a known potential difference is used. Ohms' law states that the current through a metallic conductor at constant temperature is proportional to the potential difference, thus the potential difference or current is constant.
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Prediction I predict that the longer the wire the bigger the resistance. Resistance Metals are made up of atoms. Electrons move through the metal. The metals tries to stop the electrons passing through this causes resistance. When you double the length you double the resistance. Results table Length V I R V I R V I R Average 10CM 2.00 0.81 2.46 1.76 0.94 1.87 1.75 0.88 1.98 2.10 20CM 2.18 0.56 3.89 2.15 0.57 3.77 2.09 0.56 3.73 3.79 30CM 2.33 0.41 5.68 2.31 0.40 5.77 2.25 0.39 5.76 5.73 40CM 2.40 0.31 7.74 2.41 0.32 7.53 2.36 0.31 7.61 7.47 50CM 2.50 0.26 9.61 2.47 0.26 11.2 2.40 0.26 9.23
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To find a relationship between the molecular size of different alcohols and the associated energy change involved in the reaction.
Breaking chemical bonds takes in energy from the surroundings, and is an endothermic process. When the new bonds are made between carbon and oxygen to make carbon dioxide and between hydrogen and oxygen to form water, it gives out energy. Making chemical bonds gives out energy to the surroundings, and is an exothermic process. When the alcohols react with oxygen, the total energy given out is greater that that taken in to break the bonds, and so overall, this reaction gives out energy and is an exothermic reaction.
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A manufacturer of resistors uses a variety of wires to make resistors of fixed values. You are to carry out tests to investigate how he can produce resistors with different values of resistance.
This shows that different materials will give different values of resistance even if their length and cross section are the same. Variables: Variables which will affect the resistance of the wire are: Length Thickness Material Resistivity Temperature Variable to be investigated: The variable which we are going to investigate will be the length. Prediction: I think that in the experiment, when we increase the length each time, the resistance will increase. Planning experimental procedures Independent Variable: My independent variable will be the length.
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9 75 76 75.5 10 74 75 74.5 Range 10 9 An Experiment With A Small Bubble Wrap Facing Out, Covering The Can Minutes First Experiment Second Experiment Average Starting Temperature 84 84 84 1 82 82 82 2 81 80 80.5 3 80 79 79.5 4 78 78 78 5 77 76 76.5 6 76 75 77.5 7 75 74 74.5 8 74 74 74 9 73 73 73 10 72 72 72 Range 12 12 An Experiment With A Small Bubble Wrap Facing In, Covering The Can Minutes First Experiment Second Experiment Average Starting Temperature 84 84 84
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An Investigation into the relationship between the forces applied to a length of wire and its extension.
Strain involves extension and original length therefore also bringing in extension, as I required this would be the variable that I will measure. The other variables involved, original length and cross sectional area will have to be maintained as constants as these are active variables I young's modulus. This is a specific form of Hooke's law of elasticity. The units of Young's modulus in the English system are pounds per square inch, and in the metric system newtons per square metre (N/m2).
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My experiment is safe because all of the wires are insulated and have covered ends. To carry out the investigation I will: 1. Collect together the equipment needed, 2. Set it up as in the circuit diagram below, 3. Change the length at which the crocodile clip touches the wire, 4. Record my results each time, 5. Repeat the experiment a sufficient number of times. I am going to measure the voltage and the number of amps flowing around the circuit. Circuit Diagram We worked very safely in this experiment, we did not need to wear goggles or eye protection because all the wires had covered ends on them and the equipment was safely set out on the bench.
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Prediction 1 I predict that as the wire gets longer the resistance will increase. This is because the electrons are being "pushed" around the circuit and they will collide with atoms in the resistor, as the atoms in the resistor are given more energy by the electrons they will vibrate faster and cause heat. +---------------- Electrons are pushed this way (Figure 1)
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It is more difficult for current to flow through when there are few electrons able to move. This results in a higher resistance. * Wire density: If the wire has a higher density, the resistance will be higher. This is because the wire contains more atoms in a smaller space, creating smaller and less gaps for the electrons to flow through. Because there is a lack of space, there should be more collisions of atoms and electrons. I have chosen to investigate the length of wire Prediction: In electricity, the property that changes electrical energy into heat energy, in opposing electrical current, is resistance.
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This will give me a set of results to compare my originals to. When performing this experiment I must carry out a few safety procedures. I must make sure I do not overpower the bulb as it could break.
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This is to ensure that the equipment is working correctly and ensure a fair test. For each test I am going to use 1 volt. The variable that I am going to change each time is the length of the constantan wire. To ensure a fair test I will measure the length of the wire accurately each time. To ensure that the experiment is safe I will avoid touching the constantan wire because it will be hot. Make sure that I turn off the power supply to the circuit when I am altering the distance of the crocodile clips so that there will be no chance of getting an electric shock.
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The variables are: 1) the distance the calorimeter is above the flame 2) the amount of water used 3) the temperature change of the water 4) the size of the wick 5) the alcohol I use From my preliminary work, I have decided to keep the variables as (respectively): 1) 10cm 2) 50ml 3) +10�C 4) 3.5cm 5) This variable will change, in order to achieve a conclusion to objective two. [To see how these variables relate to the experiment, please see the Method] In order for this experiment to be not only fair, but safe as well, there are basic guidelines I will use, such as; I will wear goggles at all times, and I will keep the alcohols at 2 arms' length away from naked flames (except when I am burning them)
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Another sort of resistance can be likened to water flowing through a thin pipe. The water cannot flow through as fast as there is less space available to flow. The analogy most like electricity is the water passing through a filter. The water collides with the filter and is thus slowed down; not as much water can pass through as quickly. Likewise, electrons collide with the nuclei of the metal ions in the wire. This slows down the electrons in much the same way as the filter slows down water. A wire with low resistance is like water through a grille, a wire with high resistance like water through many sheets of filter paper.
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This will increase the resistance. I will be investigating how the length of wire, when changed, affects resistance. If I was to double the length of the wire, the resistance would also double. The amount of collisions that would take place would also double as the number of atoms would double. In my circuit, I am going to connect a resistance wire. I can vary the length of the wire and record the resistance reliably. This will show me how the resistance is affected.
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