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# GCSE: Electricity and Magnetism

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Meet our team of inspirational teachers Get help from 80+ teachers and hundreds of thousands of student written documents 1. ## Coursework &#150; The resistance of wire

Once found we divided it by the current and used that to find the resistance in ohms. First a length of wire over a metre long is laid next to a metre rule. The positive crocodile clip is attached at 0cm. And the negative is moved up and down the wire, stopping at 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100cm. Each time reading the ammeter and voltmeter to work out resistance Prediction: I predict that lengthening the wire will increase the resistance in proportion to the length.

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2. ## Factors affecting the resistance of a wire

This means that resistance is directly proportional to length. When the cross-sectional area of the wire is increased the resistance decreases. This is because there is more space for the same amount of electrons to move in. If I were to increase the cross sectional area in my experiment, I would expect the resistance to be less than a smaller cross-sectional wire of the same length. When temperature increases resistance also increases. This is because the extra heat gives the electrons extra energy.

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3. ## Resistance Investigation

I predict that as the length of the wire increases the resistance will also increase in direct proportion, as there will be more particle collisions in the longer wire. In addition the free electrons in the outer shell have to carry the charge further, which also increases the chances of collision To make the experiment a fair test we will use 2 volts throughout and include a switch in the circuit, which will enable us to control that the circuit is only on when we are taking readings.

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4. ## Comparing the Energy Released By combustion of Different Alcohols

ALCOHOL ENERGY RELEASED (KJ/mol)) Methanol -659 Ethanol -1279 Propan-1-ol -1899 Butan-1-ol -2519 The negative values mean energy is lost from the compounds and is therefore given out as heat or light as an exothermic reaction. The graph shows that as the length of alcohol chains increases the energy released by combustion will also increase directly proportionally. This is shown by the straight line passing through the origin on the graph on page 6. This is because the longer chains have give out more energy from the bonds formed in the products than the energy that went in to break the extra carbon and 2 hydrogen bonds.

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5. ## Planning an investigation

Once the results were obtained I found out the resistance of each wire via voltage divided by amperes. The safety aspect of the investigation I keep the voltage to a minimum of two amps and when of the shorter lengths of wire keep it live for shortest time possible to avoid the wire heating up. The accuracy of human error and visual gauges is limited the voltage is limited to 0.02 were the ampere meter is limited to 0.2. Prediction From a secondary source Roger Muncaster a-level physics textbook author state ohms law.

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6. ## The strength of an electromagnet

2. The longer the wire, the more coils will be. Therefore the stronger the magnet will be. 3. The more or current is, the stronger the electromagnet will be. Method: First of all we set up the equipment as shown in the diagram and according to the circuit. The first wire length we used is 100cm. As the circuit is completed we on the power pack and set the current on 1 amp. After that we hanged as many as paperclips the magnet could handle and recorded the result down.

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7. ## What affects the resistance of a piece of wire-Analysis

I am now sure that part of my prediction was correct-As the wire gets longer the resistance increases. The second part of my prediction-The resistance will be proportional to the length was not obvious from my results table so I drew two graphs-Length against amps and length against resistance.

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8. ## Investigating the heat of combustion of a series of Alcohols

3 X 497 = 1491 Total Energy in = 4812 kJ Total Energy out = 5472 kJ Energy Released = 4812 - 5472 = -660 kJ When a bond breaks, energy is taken in so that it has enough energy to break the bond. Also when bonds are formed, energy is given out in an exothermic reaction. Overall, more energy is given out than is taken in so the reaction as a whole is an exothermic reaction. The total energy given out is the figure at the end.

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9. ## How the Temperature of Water Is Affected By the Time It Is Heated.

So the more substance I have means that it will take longer to heat up, if I have less substance then it will not take as long. * The substance I heat - different liquids have different specific heat capacities. Specific heat capacity (as found in my "Key Science - Physics" textbook) is the energy needed to raise the temperature of 1kg of material by 1?C. Specific heat capacity is always a constant for the substance but because different substances have different consistencies and structure then they have different specific heat capacities and so will need more or less energy to heat them up.

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10. ## Energy Resourses Investigation

Then after millions of years and hundreds of earth movements the swamp was compressed concentrating this energy into coal oil and gas. Biomass also was only created because the sun has enough energy to feed the plants that start off the chain process. Food energy is again also created I this way weather animal or vegtable this is because the vegtable matter absorbs the suns energy through photosynthesis animals then absorb this energy from the original plant and then from each other all the way up the food chain .

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11. ## Investigation: Factors affecting the resistance of a wire

So if the length is doubled the resistance should also double. This is because if the length is doubled the number of atoms will also double resulting in twice the number of collisions slowing the electrons down and increasing the resistance. My graph should show that the length is proportional to the resistance. Method: In my experiment I will measure the resistance of different lengths of wire, to do this I will use a ammeter and a volt meter, connected to a power pack an incorporating the wire into this circuit as shown in the diagram.

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12. ## 1st law of thermodynamics

Instead the temperature of the ice rises until it reaches zero degrees Celsius whereupon it begins to melt. During the entire melting process the contents of the bucket remain at zero degrees, however the room temperature would drop indicating that it was putting heat energy into the melting process. This heat energy is described as latent heat. Specific heat The specific heat capacity of a solid or liquid is defined as the heat required to raise unit mass of substance by one degree of temperature. Some substances have more resistance to temperature change than others so more energy is required to alter the temperature.

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13. ## What factors affect the resistance of wire?

* Temperature - For metal conductors, resistance increases with temperature. For semi-conductors, its decreases with temperature. I am going to investigate how length affects the resistance of a wire. I will change the length of the wire through a range of readings. My prediction is that as the wire gets shorter the resistance become smaller e.g. if it is half the length it should have half the resistance. I think this because the wire is full of atoms and the electrons have to try and get through it. So if the wire is short there is less atoms so the electrons will travel easier.

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14. ## What Factors Effect the Resistance of a Wire?

* How much light is on the wire. I have chosen to investigate how the length of the wire effects its resistance as it is the simplest of all the above to measure. The other factors will have to be kept constant in order for the experiment to be a fair test. The thickness of the wire will be easy to keep the same throughout as will the material that the wire is made from. However, the temperature of the wire and how much light there is on the wire will be hard to keep constant.

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15. ## Trolley Mass and Gravitational Field Strength Investigation

As the mass is increased, so does the potential energy because the gravitational field strength has more mass to push down. Potential energy changes into kinetic energy as the object starts to move and this is because the potential energy, which is what the trolley is capable off, changes in kinetic energy which does what the trolley is capable of. There are two things, which would alter the speed of the trolley, and they are air resistance and friction. Friction and air resistance will increase as the speed of the trolley increases.

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16. ## Physics Resistance Investigation

Cross-sectional area of wire ==> The formula R = �I shows us that the cross-sectional area affects resistance. A This will be done again by using the same wire throughout the experiment. Prediction I predict that the resistance of the wire will be directly proportional to the length. Atoms in the material which electricity is passed through cause resistance against the electricity producing heat energy. In the structure of the atoms of materials which conduct electricity the outer shell has free electrons.

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17. ## To discover how length and cross sectional area of a wire affects the resistance of a wire.

* I will keep the cross-sectional area the same when monitoring the length and vice versa Method: * I will set up the apparatus as shown in the diagram above. * When a current is flowed through the wire I will record the readings on the ammeter and the voltmeter in to a table. * I will then use my results in the formula R=V/I to calculate the resistance of the wire. * I will then increase the variable I am analysing and record the data I have mentioned.

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18. ## Why does a squash ball bounce higher when it is warmed up?

To ensure the human body does not affect the temperature, tongs will handle it. Temp (?C) Temp (Kelvin) R1 R2 R3 R4 R5 Average 10 273 39 44 37 33 39 38.4 20 293 42 41 36 44 43 41.2 30 313 57 48 51 29 53 53.8 40 333 71 62 63 65 58 63.8 50 353 67 70 79 68 68 70.4 Results I am going to work out pressure and predicted hang time using the following formulas.

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19. ## Resistance of a Wire Coursework

My hypothesis is: "The longer the piece of wire is, the greater the resistance will be" To back up my hypothesis I used scientific evidence from Ohms law. Ohm was a German physicist who in 1827 developed this law. It states that's the ratio of the voltage across a conductor to the current flowing through it is a constant, the resistance. Ohm also found that the resistance of a conductor depends on its thickness, length and the material it is made from.

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20. ## Investigating One Factor Which Affects the Resistance of a Wire

across it (providing the temperature remains constant). I am going to test this law. The four factors that affect resistance are: Lengths of the wire - the longer the wire, the more atoms there are for the electrons to collide with resulting in the loss of more energy. Thickness of the wire - the larger the cross-section, the more charge that can travel simultaneously through a given length. It is like a motorway. Material it is made up of - some materials have less resistance than others. They have fewer atoms therefore there are less atoms for the electrons to collide with resulting in a lower loss of energy.

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21. ## Electromagnets - an investigation on electromagnets, our aim will be to find out what effects the strength of an electromagnet and how it affects it.

Electromagnets are used every day in a lot of devices such as relays, circuit breakers, door/alarm bells and anything else that is found to have a motor in it. My Prediction We all know that a wire carrying a current will produce a magnetic field around it self. This means that if the wire is compressed or coiled into a solenoid then the field will be more compact and therefore very much stronger. So, if more of the wire is wrapped around the iron bar then the electromagnet should become much stronger and stronger each time.

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22. ## To investigate how the electrical resistance of a wire changes in relationship to it's length.

A property of the atoms of all conductors is that they have free electrons in the outer shell of their structure. all metals can be used as conductors. some are better than others, but they all look something like this: As a result of the structure of all conductive atoms, the outer electrons are able to move about freely even in a solid. When there is a potential difference across a conductive material all of the free electrons arrange themselves in lines moving in the same direction. This forms an electrical current. When charged particles (current) encounter fixed particles (metal)

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23. ## The Electrical Resistance of a wire

Planning When planning and designing my experiment, I will consider what factors will affect the resistance of a wire and decide upon which one will I will be the variable. Temperature: Conductivity is less at higher temperatures. When the wire is heated, the atoms in the wire will vibrate more, because they'll have an increase in energy. This will cause more collisions between the electrons and the atoms, causing resistance to rise. This would be a difficult to do, as we are not provided with the proper equipment to carry it out effectively. Material: Different materials conduct better than others.

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24. ## What factors affect the resistance of a wire?

The bigger the resistance of a conductor the harder it is for electric charge to flow through it. For a given voltage applied to it, the current would be less. It is like water flowing downhill in a river. If the bed of the river is smooth the water can flow easily, and more can get through on a given time. But if the bed of the river is rocky the water can't flow so easily. It will move downhill more slowly and a lot of energy is wasted - you can hear the noise and see the water being thrown up in the air.

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25. ## Resistance of Wire Investigation

A greater cross-sectional area results in a smaller resistance to the flow. Resistivity is a measure of the ability of a material to resist the flow of an electric current. Resistivity is represented by the Greek letter rho, , and is measured in Ohm-metres (? m) . Resistivity is equal to the resistance R of a material such as a wire, multiplied by its cross-sectional area A, and divided by its length l. This is given in the formula: = RA/ l Usually, a material's resistance increases with increases in temperature.

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