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GCSE: Electricity and Magnetism
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The smaller the cross-sectional area of the nichrome wire is e.g. 20swg, the fewer channels of electrons in the wire for current to flow and as a result of this the resistance will be high but having a lower area of wire leaves it more susceptible to a heating effect. However, when the cross -sectional area increases to a value of 36swg for example the resistance will decrease as there are more channels of electrons in the wire (This can be seen in the following diagrams; figure 1 and figure 2).
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What factors affect the resistance of a wire?The reason why the length of the wire affects the resistance of the wire is because if there is more wire for the electrons to travel down, they are impeded by more stationary atoms
The reason why the thickness of the wire affects the resistance of the wire is because depending on the thickness of the wire, it could allow or prevent more electrons to flow through the wire; therefore in theory if the wire is thinner there should be a greater resistance. The reason why the material the wire is made of affects the resistance of the wire is because depending on the density of different wires, some are more dense and should in theory, resist the amount of electrons able to run through the wire as there are more stationary atoms blocking the path, therefore if the wire is less dense it should resist less.
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For example, it would be very difficult to keep the temperature of the wire constant. This is because the wire heats up the longer it is in use, and it would also be difficult to measure the actual temperature of the wire. I thought number of components would take a lot longer to set up, needing more and more wires in the circuit. Type of wire is a discreet variable, so I could not identify a proportional relationship, meaning no line graph in my conclusion.
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The aim of this investigation is to find out how the resistance of a wire is affected by its lengths. I will do this by changing its lengths and working out each lengths potential difference and current.
The independent variable will be the length of the wires as we are trying to find out its affects on the resistance. The independent variable affects the dependant variable as in that when you change the independent variable the value of the dependant variable will change. The dependant variable in this case would be the resistance of the wires and it will change as the length of the wire changes. Hypothesis: I think that the resistance of the wire will be higher when it is longer.
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Resistance of a wire. Jack has been given a second hand D.C. dynamo and lamp. He wants to attach these to his bicycle and produce most light without blowing the bulb. What wire should he use?
We also had a voltmeter in parallel to the wire we were testing. The readings we take off the ammeter and voltmeter allow us to figure out the resistance using a simple equation: Voltage � Current = Resistance. Our circuit looked like this... A variable resistor allows us to control the current going through the circuit. We needed to keep it as low as we could to avoid a heating effect in which ohms law would not take place and our results would not be accurate. Type Of Wire Current (I) Voltage (v)
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Length- Length is the variable that I will be changing and will be basing my whole investigation around. As the length of the wire increases the resistance through the wire will also increase. This is because in a longer wire there is more electrons colliding with the metal ions as they travel along the wire than there would be in a shorter wire. This means that there are more collisions between the electrons and the metal ions which make the atoms vibrate more which makes the metal hotter.
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The equipment we used to make our results accurate is an ammeter which measured the current of the electrons through the wire. We used a voltmeter to measure the potential difference across the wire. We also used a variable resistor so that we were able to control the voltage to help us get our expected results. The current is changed throughout the experiment so that we could get more than once for each length so that we get a good average.
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Long wires are more resistant than short wires because there are more electrons in a longer wire. Resistance cannot be measured, however you can calculate resistance with a formula ( voltage = current x resistance ). To calculate resistance you need to know voltage and current when you find these two you divide them, then you know what resistance is. Resistance increases whenever the current flows in a wire (when It heats up) it happens as a result of energy loss. PREDICTION; I predict that that the longer the wire is the higher the resistance, because there will be more free atoms colliding with eachother.
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We are going to be investigating the resistance of a wire when measuring at different lengths. We will be using four types of wires which are: * Copper, * Manganese, * Constantan * Nickel chrome. We are going to be measuring the resistance at six different lengths: * 10 * 25 * 40 * 55 * 70 * 90 The swg of the wire will be 28 for each experiment which will keep it a fair test. Also, we will repeat our experiment 5 times for each length as this way our results will be more reliable and more accurate.
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Some materials are better conductors than others. * Length- As we will find out in the following investigation, the longer the wire the higher resistance. The electrons collide with fewer ions in a shorter wire than in a longer one. * Thickness- The thinner the wire the more resistance it has. * Temperature- Metal ions vibrate more when it is hotter so the collisions with electrons are more likely, this means that the higher the temperature, the higher its resistance. Equipment The Equipment needed for this investigation is: - 2 x meters - one multimeter will measure the voltage (voltmeter)
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* When two electrically charged materials are brought together, they exert a force on each other. Materials with the same charge repel each other whereas materials with different charges attract each other. * Current is the rate of flow of electrical charge. Electrical charge can easily flow through metals because they contain conduction (delocalised) electrons. These electrons are not confined to a single atom. This is the reason why metals are food conductors of electricity. Insulators cannot conduct electricity because all the electrons are held within atoms * A charged body can be discharged safely by connecting it to earth with a conductor (e.g.
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The truth is that most of us would be terrified at the prospect of living without these luxuries as they do massively reduce human effort, but what happens when the envelope is pushed and machines step over the line. Technology is all around us and has been developed for our benefit. For instance, people wanted an easy form of communication, the telephone was invented. People needed information fast, thus was created the internet. The fact is that technology had made us who we are today, some argue it has made us lazy as everything we do has something in one
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This is ohm's law, meaning that changing the voltage would also change the current by the same amount the voltage was changed by, therefore keeping resistance the same. This is shown by the formula I= V/R, where (I) is the current, (V) is the voltage and (R) is the resistance. Another factor that we can test is changing the diameter of the wire. A thinner wire would provide more resistance because there is less space for the electrons to pass, which would then cause the battery to work harder to push the wire around the circuit as there is more resistance.
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I am going to build a sensor for a vehicle fuel gauge. It will sense how much petrol or water there is in the tank.
I also had to replace some of the equipment which were damaged and made the results inaccurate. This sensor is used in transports such as cars, motorcycles, trucks etc. and is a very important component. Without it the driver would not know how much fuel is left in the tank. It works by having a float or something similar attached to a rod, and the other side of the rod is attached to a rotary potentiometer. As the float moves up or down with the amount of fuel, the rod will be twisting with it, and so will the rotary potentiometer, and this will produce a voltage which will indicate the fuel level in the tank.
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I had set up this investigation to see whether the voltage flowing through a light bulb affected the resistance. I conducted the investigation by setting up a simple circuit, which is illustrated by the circuit diagram below. Equipment - * Filament Light Bulb - To test the resistance of a filament light bulb * Connectors - To connect the circuit together * Power Supply - To power the circuit so the resistance can be calculated * Rheostat - A variable resistor so the voltage can be altered accurately (I had chose to use this because I could alter the voltage flowing through the current accurately)
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I have certain hypothesis of how temperature affects resistance (ii) I have chosen enameled copper wire as I will be using long lengths I do not want to short circuit the wire when they are wrapped hence the enamel. I chose copper because it is meant to be used as an electrical conductor (e.g. wire) compared to nichrome wire which is for use for heating elements (this would affect temperature and make my investigation un reliable) and constantan which is used for making resistors (heat doesn't change its resistance much)
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Making sure you apply no pressure when dropping the ball bearing, to make it as fair as possible. Repeat this 3 times for 10 different heights in my case (3 x 10cm, 3 x 20cm, 3 x 30 cm, 3 x 40cm, 3 x 50cm, 3 x 60cm, 3 x 70cm, 3 x 80cm, 3 x 90cm, 3 x 100cm)
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I will do this for different lengths of nichrome, simultaneously recording my results. Nichrome Wire Length List of materials used: 1. Wire cutters 2.
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Circuit Breakers. A circuit breaker is a device that automatically breaks an electrical circuit whenever the circuit becomes overloaded or an unintentional short circuit occurs.
An unintentional short circuit occurs when electricity traverses a path that is different from what has been intended. This usually happens when the insulating material or layer between two conductive materials breaks down or when a conductive material is directly introduced between these two conductive materials. This results in an unintended direct flow of charge from one node to another. This may result in overheating, circuit damage, explosion, and even fire.
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However unfortunately there is no readily available source of molecular hydrogen (H2) to be found on our planet. There is lots of hydrogen, but it is found as part of larger molecules, most commonly water or hydrocarbons. To be able to use hydrogen in a fuel cell, those hydrogen atoms must be stripped from hydrocarbons and reformed into H2 or electrically disassociated from oxygen in water. This is factual as hydrogen gas like helium gas just floats off into space as it is lighter than the gases that make up the air.
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The in 1918 a polish scientist developed a method to produce single-crystal silicon. This is a semi-conductor which can be adapted to free electrons when it is exposed to a light source. Today PV cells are being used all over the world in everyday situations. There are villages in the US which get all their electricity from solar cells alone. There are both advantages and disadvantages to Photovoltaic cells; an advantage of PV cells is that they require daylight not direct sunlight.
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The resistance of a piece of wire is dependent on its temperature, length, cross-sectional area and the type of metal the wire is made of.
The free electrons are given energy and as a result move and collide with neighbouring free electrons. This happens across the length of the wire and thus electricity is conducted. Resistance is the result of energy loss as heat. It involves collisions between the free electrons and the fixed particles of the metal, other free electrons and impurities. These collisions convert some of the energy that the free electrons are carrying into heat. Resistance is usually given the symbol 'R'. The unit for electrical resistance is the ohm. Ohm's law is the voltage drop (V) across a resistor proportional to the current running through it.
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Diameter (swg) Voltage across the wire (V) Material of Wire Current (Amps) Resistance (?) 90 90 90 90 90 34 34 34 34 34 0.63 (2) 2.41 (4) 4.08 (6) 6.00 (8) 7.80 (10) Constantan Constantan Constantan Constantan Constantan 0.06 0.24 0.42 0.62 0.80 0.37 2.17 9.71 9.70 9.75 80 70 60 50 40 34 34 34 34 34 4.05 (6) 4.04 (6) 4.01 (6) 3.98 (6) 3.83 (6) Constantan Constantan Constantan Constantan Constantan 0.47 0.53 0.60 0.74 0.91 8.62 7.62 6.68 5.38 4.21 100 100 100 36 32 20 3.20 (6)
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Thus more the time, the higher the temperature will be until a certain point. This is the boiling point, and this is when the molecules have reached the maximum point, and are on the point of transforming into another state of form gaseous. Apparatus * A Calorimeter * A Thermometer * A Electric Weighing Scale * A Power Pack * A Stirrer * Water * A Stop Watch * A Lid * An Ammeter * 6x Wires * A Voltmeter * An Immersion Heater Diagram Method 1.
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Thus as resistance drops, more current will flow through the electromagnet causing a larger magnetic field. Apparatus: --> Soft iron core ( a long nail) --> Copper wire of three thicknesses --> Power supply --> Metre rule --> Connecting wires and alligator clips --> A magnetic compass --> Ammeter Procedure: 1. Take 80cm of a chosen thickness of copper wire. 2. Tightly wind it around the soft iron core 40 times. 40 coils should be on the core. 3. Leave a little wire towards the ends for connections to be made.
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