GCSE: Electricity and Magnetism
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Electrical resistance
In a stretch of wire, collisions of electrons take place. If the length of the wire was doubled, I predict that the number of collisions would also double, therefore increasing resistance, so if the wire was half of the original size the number of collisions would be halved compared to what they were in the first place. The thickness of the wire also affects the flow of electrons and the speed at which they travel. If the wire was thin there would be many collisions amongst the electrons and they would be squeezed together, not moving freely and therefore the speed is decreased.
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Investigation of factors that affect resistance of a wire
The first thing I had to do in this coursework was decide upon the factor that I would be investigating. I narrowed my list of variables down to 3 : Temperature, material and length of the material. In order to choose which factor to investigate I looked at my options and looked at the advantages and disadvantages of each as well as how effective and easy to measure they are. Variables 1.Temperature : If a wire is heated the atoms in the wire start to vibrate because of the increase in energy.
 Word count: 1957

Electricity Investigation
A battery acts like a pump providing chemical energy to push electrons around a circuit. Cells have different pressures called electromotive force or e.m.f and is measured in volts. Across a lamp there is an electrical pressure difference called the potential difference (p.d) or voltage which is measured in volts using a voltmeter. The voltmeter is always used in a parallel circuit across a component. The voltage across the lamp equals voltage across the cell. Ohms is used to measure resistance. Ohm's law is: " the current flowing through a metal wire is proportional to the difference across it (providing temperature remains constant)"
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The affect the length of a wire may have on the resistance.
Judging by this theory I believe that if you increase the length of a wire, the resistance will also increase. The relationship between the length of a wire and the resistance is directly proportional. The following is an equation that can be used to find the resistance using the current and voltage:  Resistance (R) = Voltage (V) Current (I) Resistance is defined as the difference in the amount of volts across the object when there is a flow of current of 1 amp.
 Word count: 1943

Resistance Investigation
In a piece of metal, the atom are packed together in a regular pattern this is called the lattice. They are packed so tightly some of their electrons become detached from their atom. These 'free' electrons move around in the space between the atoms they are shared between the atoms in the piece of metal. The metal atom carries positive charge because they have more protons then the electrons. The positive and negative charges attract each other, so the whole arrangement is held closely together. The free electrons explain why metals are so good at conducting electricity. The movement of the electrons is what we call and electric current.
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How the area of a wire affects the resistance in a circuit
At higher temperatures the particles move more quickly, increasing the collision of the free electrons. Possible Input Variables Wire area Wire thickness Wire length Applied voltage Material Taught connections Crosssectional shape Insulated Density of wire Coiled or not Temperature Preliminary Experiments Easy to measure? Easy to change Wire area V V Wire thickness X X Wire length V V Applied voltage V V Material X V Taught connections X X Crosssectional shape X X Insulated X V Density of wire V X Coiled or not V V Temperature V V Applied I or V by a double cell which is measured by digital volt and ammeter.
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How does the length of a piece of Nachrome wire affect its electrical resistance.
The resistance of a wire is inversely proportional to its area of crosssection. Material The material of which the wire is composed is another important factor to be considered when deciding the length and gauge of wire for a particular resistance. Silver is the best conductor, but copper, the next best, is cheaper and is used for connecting wire and in electric cables. Resistors are used in circuits to limit the current in each branch of a circuit. I f resistor is replaced by one of lower resistance in a circuit, the current will be greater and this may cause overheating and damage to other components in the circuit.
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To investigate the factors affecting the resistance of a piece of wire.
The standard symbol is R and the symbol for ohms in electric circuits is the Greek letter omega, ?. Electrical resistance is inversely proportional to electrical current. This means that if one doubles, the other halves or if one triples, the other decreases by a factor of three. It is written as I ? 1/R with I being the symbol for current and R the symbol for resistance. The resistance of a wire is determined by four main factors: 1) Length The length of a piece of wire is related to its resistance. I predict that the longer the wire, the higher the resistance as the electrical charges have further to 'travel'.
 Word count: 1551

Wire Resistance Investigation
Sellotape Fair Test: I will make this test a fair test by keeping all the variables constant. By keeping the room temperature same each time and the same type of the wire the same each time. The wire will have to be pulled tight and tapped to both ends. Then I will carry out the experiment three times to get three sets of results. I can then work out the average and make graphs to show my results with a line of best fit. Prediction: I predict that if you increase the length of wire you increase the resistance.
 Word count: 1797

To investigate how the thickness and length of the wire in a circuit effects the flow of electrons through a circuit
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. Resistance is encountered when the charged particles that make up the current collide with other fixed particles in the material. As the resistance of a material increases so to must the force required to drive the same amount of current. In fact resistance, in ohms(R) is equal to the electromotive force or potential difference, in volts (V)
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Find out if there is a relationship between the length of the resistance wire and the value of resistance by using different lengths of resistance wire.
Variablesthings that might affect the resistance 1. Length of wire 2. Thickness of wire 3. Temperature of wire 4. Type of wire Variable to investigate We are going to investigate how the length of resistance wire will affect the resistance. Prediction I predict that the longer the resistance wire, the higher the value of resistance. This will happen because resistance wire is used to reduce the amount of current flowing in a circuit. The atoms in resistance wire are arranged so that it is more difficult for the free electrons to move and so they bump into each other this causes a higher resistance and so they cant carry the electric current as well.
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Resistance of a wire
Each collision produces heat. When an atom is heated it starts to vibrate. It is therefore moving, on a fixed point, but moving. This movement from side to side blocks the electrons creating more resistance. Chances are that there will be more collisions and so more heat and the process starts again (See Diagram Below). However if I only use a small current, maybe less than 1 Amp this may reduce the heating effect. I only want to see what effect the length of the wire has on the resistance of the circuit and if I changed more than one variable the experiment would be unfair and inaccurate.
 Word count: 1532

Investigate the effect of one or more physical characteristic of a piece of wire upon its resistance
Thickness and type of wire must remain constant, as does the voltage across it. For this experiment I will need: 1m of wire (30sgg Constantan) 1 Ohmmeter 2 Crocodile Clips 2 Wires (for attachment of crocodile clips) Diagram: Method: Take the 2 short wires and place one end into the ohmmeter and to the other, attach the crocodile clips. Complete the circuit by placing the length of wire you will be testing (I am using a range from 0cm100cm in 10cm intervals)
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Youngs Modulus of Elasticity of Nicrome Wire
the distance will be measured, and then as subsequent weights are added, the distance will be checked again to see if any slip has occurred, and then if slip has occurred, it will be taken into account and not added to the extension. Procedure First several diameters of the Nicrome wire will be obtained, with a zeroing of the micrometer first, then obtaining an average. Note the micrometer will be cleaned first, in case any foreign particles interfere with the measuring of the Nicrome wire.
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The Resistance of a Wire
In equation this is R=KL Where K is some constant and L is length. Area of wire Again this is a physical characteristic that will remain constant regardless of all other variables. However it will be easier to change the length of the wire, as changing the diameter will mean switching to a completely different gauge of wire. However when several ranges of data have been taken for one wire gauge, then this variable could be changed. Cross sectional area of wire is therefore an independent variable that will be changed if time allows.
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Investigate if the length and crosssectional area affects resistance through a circuit.
When the voltage is increased, the current increases. For a particular metallic conductor, the current is directly proportional to the voltage, as long as the temperature stays the same. I also found out from reading scientific textbooks that resistance is caused by the free electrons colliding with the ions in the metal lattice. Every time the electron collides with an ion, it loses energy in the form of heat and the result of this decreases the speed. Metallic conductors Metallic conductors have free electrons, which form a gas, which then can fill the entire volume of the metal.
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Resistance of a Wire Investigation
Changing the crosssectional area of the wire should also change the resistance. Making it larger lowers the resistance because the electrons would have more space to move in and so it would be much easier for them to move to the end of the wire. Changing the material means that there are different numbers of atoms and electrons so the resistance will change. If there are more atoms and fewer electrons then the resistance will increase as fewer electrons can reach the end.
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How the area of a wire affects resistance
This means that also there will be twice as many electrons getting through twice as many gaps. Ohm's Law V=I/R is the famous equation and law. This law states that the current through a metallic conductor (wire) at a constant temperature is proportional to the potential difference (Voltage). The size of electric current flowing trough a conductor, depends on the voltage across it, and the resistance of a conductor. If the voltage increases the current increases. Possible Input Variables Wire area Wire thickness Wire length Applied voltage Material Taught connections Crosssectional shape Insulated Density of wire Coiled or not Temperature Preliminary Experiments Easy to measure?
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Gcse Physics Investigation: Resistance of a Wire.
To keep the experiment a fair test, I must be sure only to change ONE of the variables, all the other factors must be kept constant. If I did not keep the other factors constant the results may be incorrect and there would not be any pattern. Problems that may occur. If I were testing how the thickness of the wire affects resistance and I altered the length of the wire each time I changed the thickness of the wire, the results would not be correct.
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Analyze the cause of the lack of development of renewable energy sources.
Solar cells are thin wafers of silicon which, exposed to sunlight, produce DC electric current. Today, solar equipment for a normal household is about $15,000. For a lot of people this is too much keeping in mind that it takes many years to use electricity worth that amount. Modern photovoltaic modules are able to produce Sebastian Seidel 2 electricity at 20 cents to 30 cents a kilowatt hour (Flanigan 2). In comparison in Texas , a kilowatt hour produced by fossil energy is about 7.6 cents (Linden 1).
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Investigating how the length of a wire Effects resistance.
Varying cross sectional area effects resistance because if the wire is thicker it allows the electrons to flow more freely, so the resistance is then lower. The temperature affects resistance because as the metal's temperature rises its constituent atoms vibrate more vigorously. This increases the amount of interaction between the atoms and the current carrying electrons. The flow of electrons is impeded, increasing the resistance. The length of a wire affects resistance because the longer the wire, the more particles there are to get in the way of the flowing electrons.
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Investigating the Factors that may affect the Resistance of a Piece of Wire
* Changing the current. * Changing the thickness of the wire. * Changing the length of the wire. * Changing the material of the wire. * Changing the temperature. These variables are all viable to use except changing the temperature of the wire because this is very difficult and time consuming. Changing the length of the wire is very accurate and changing the current is easily done because I would have to slide the variable resistor back and forth to change it. Changing the thickness of the wire is one of the most reliable variables because temperature, current or voltage can affect it.
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Does The Length Of The Wire Affect The Resistance?
The wire I will use will be consistine. I will be making the wire shorter as the investigation moves on, but I don't want to make the wire too short otherwise it'll just melt (see 'Pretest'). I will test each length of wire three times and find the average of the three. I will need to consider safety during the investigation. To keep everything as safe as possible I will not touch anything metallic whilst the power pack is turned on. I will not cut the Consistine to a certain length. I will also wait for a while until the wire cools otherwise I may burn my hand.
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To investigate how the length affects the resistance of a wire.
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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Investigation into the Resistance in different lengths of wire
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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