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# GCSE: Electricity and Magnetism

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• Marked by Teachers essays 19
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1. ## Ohm's Law coursework

4 star(s)

at a constant temperature is proportional to the potential difference (voltage). Therefore V � I is constant. This means that the resistance of a metallic conductor is constant providing that the temperature also remains constant. Furthermore, the resistance of a metal increases as its temperature increases. This is because at higher temperatures, the particles of the conductor are moving around more quickly, thus increasing the likelihood of collisions with the free electrons. The variables in this investigation are: - The length of the wire - The cross-sectional area of the wire - The material of the wire - The temperature of the wire Input: * The length of wire.

• Word count: 1989
2. ## Resistivity Coursework

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Constants are current (I), cross sectional area of wire (A) Resistivity (?) and temperature of the Nichrome wire. An R against L graph must look like this, (look below,) if resistance and length are directly proportional to each other. A4c: Detailed Plan * confirm power supply unit is at 0v * construct apparatus as illustrated in diagram * connect voltmeter negative crocodile clip on 0.100m * increase current to 0.30A * take reading from voltmeter as quickly as possible for the wire to remain at the same * switch off power when entering the reading into required data * connect the voltmeter negative crocodile clip to increased 0.200m * repeat process till I reach 1.000m * repeat the whole process again but with 0.60A * plot a graph of R vs.

• Word count: 1532
3. ## Draw stress and strain graphs for the metal copper and the alloy constantan. Calculate the figures of young's modulus for copper and constantan. Discuss the physics involved.

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I have included a diagram of the set-up (Figure 1) below which was used to obtain the results I was given. Figure 1 (SOURCE: AS PHYSICS CDROM) The experiment works by a G-Clamp holding the wooden block steady, this will place pressure on the wire to keep it steady at the clamped end. The cardboard bridges keep the wire straight and in place throughout its length. The pulley allows the wire to move freely along it to keep friction minimum. As load is increased this puts pressure on wire and it may extend in length, which is the variable I will be measuring.

• Word count: 5539
4. ## Investigation into Energy Released From Burning Various Alcohols.

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The time left for the alcohol to burn will also affect the results, as the longer it is left to burn, the more energy will be released. Finally, the height of the water above the flame will affect the results. As the energy is released, some of it will be dispersed into the air before reaching the water. With a larger distance between the water and the spirit burner, there would be more time for the energy to disperse, and the amount of energy in the water would be lower than if the water was closer to the spirit burner.

• Word count: 3862
5. ## Thermal insulators.

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Which means that I need something that is a bad thermal conductor (good thermal insulator) to keep the amount of conduction to a bare minimum? Plan I am planning to test five materials (paper, cling film, cloth, bubble wrap and plastic) and one control, three times and find the average (to ensure accuracy). Whichever material changes the temp of the water the least is the best insulator. I will wrap them around a 200ml beaker (no lid) and fill it with 200ml of boiling water.

• Word count: 1014
6. ## Investigate young's modulus behind Constantan and Copper.

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By using this program, I will be able to achieve very precise results. Method: I will firstly collect the various equipment I will need which includes: A G clamp, wooden blocks, pulley, mass hangers with slotted weights, copper and constantan wire samples and a ruler. I will measure using a micrometer, the diameter of the wires and the length with a meter ruler. I will measure the length of the wires in metres and measure off very accurately to one decimal place.

• Word count: 3952
7. ## The factors affecting the resistance of a metalic conductor.

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V I V = IR R= V/ I V= Potential difference in volts (V) I = Current in amps (A) R= Resistance in a unit is called an ohm () The graph below shows the relation between the current and the voltage of a conductor, showing that as the current increases the voltage increases. This is what is termed as Ohm's Law. In order to find the resistance of a conductor, the gradient of the graph is found out using the formula: Gradient of the graph = I/V Whereby R = 1/gradient FACTORS AFFECTING THE RESISTANCE OF A WIRE: There are four external factors that influence the resistance in a conductor.

• Word count: 5381
8. ## Investigation into the Physics of a Light Dependent Resistor.

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According to Ohm's law, the resistance falls in the LDR as the current throughout the circuit increases. The reason for this increase in current is due to the greater number of charge carriers in the semi-conductor inside the resistor. In this case, the charge carriers are electrons. This increased number of electrons when light intensity increases, raises the semi-conductor's Conductivity and therefore lowers its Resistivity as the two values are inversely proportional. It is only reasonable to say that as the current through the circuit increases, so too will the voltage across the LDR. A Quantum Explanation for the behaviour of an LDR I have already said that the increased voltage across an LDR is due to

• Word count: 2131
9. ## Factors Affecting The Resistance Of A Metal Wire.

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Preliminary Work 4. Copper wire - 0.247mm diameter Length Current (A) Voltage (V) Resistance (?) 10cm 0.400 0.150 0.375 60cm 0.370 0.100 0.270 Nichrome wire - 0.247mm diameter Length Current (A) Voltage (V) Resistance (?) 10cm 0.300 0.630 2.100 60cm 0.190 1.130 5.947 Nichrome wire - 0.457mm diameter Length Current (A) Voltage (V) Resistance (?) 10cm 0.380 0.140 0.395 60cm 0.290 0.600 2.000 From the results, it can be seen that the nichrome wire with a diameter of 0.247mm had the greatest variation within the results, so this wire will be used.

• Word count: 1870
10. ## To investigate how the resistance, R, of a length of wire, l, changes with diameter, D and determine the resistivity of the material the wire used.

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The length is also an issue as the longer the wire the higher the resistance because the electrons have to travel past more atoms and collisions between the electrons and the atoms are more likely then in shorter wires. Resistance should also be proportional to the length of the wires. So, I have decided on using a length of 1m. In a metal, conduction electrons are free to move the fixed positive ions, when a voltage is applied i.e. a battery source; the free electrons are repelled by the negative terminal and attracted to the positive one.

• Word count: 4719
11. ## An Investigation To See How Resistance Can Be Changed By Variables.

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Current- this will be kept low so will not become hot, and effect resistance. A set value will be decided. Temperature-the higher the temperature the wire is at the more resistant it becomes and will be cheap low enough not to let the temperature increase. Equtions; R = V I Resistance is equal to Voltage/Current R L C.S.A Circuit; Outline Plan; * The variable I will be changing is "length of Constanton wire." * I will find the length in a pre-test. I will also combine the to together to find out the range of length with the wire type.

• Word count: 2941
12. ## How does the power dissipated by a light bulb vary with voltage?

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Graphs This is what I think my two graphs will look like: P/W P/W Voltage/V Voltage2/V2 1. The first graph will look like this because as the voltage increases, the current also increases. As they both increase, the power increases by a greater amount each time so the graph will have a curved line. 2. The second graph will look like this because as the power and voltage2 are proportional. This is shown by the equation P = V2/R. If the resistance of the light bulb remains constant, power and voltage2 increase proportionally.

• Word count: 2603
13. ## Investigation in resistance in wires

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This will give me a larger group of data than if I just increased one of them. I will need to use the preliminary tests to work out the gaps I will be increasing them by. Hypothesis I predict that, the length of the wire will be proportional to the resistance; therefore if the length of wire gets longer the resistance will get greater. My prediction is that the shorter the wire the higher current will be and the longer the wire the lower the current will be at each voltage section.

• Word count: 4433
14. ## Resistance of a Wire

4 star(s)

Material of wire - wires of different densities will block more or less electrons Temperature - the vibration of warm molecules makes them more likely to collide with electrons, and resistance increases with temperature. Variables Independent- length Dependent - Voltage, current to measure, resistance Controlled - Temperature, material of wire, cross sectional area Circuit diagram Method 1. set up apparatus as shown above 2. measure out a 1m length piece of wire and connect it to the crocodile clips 3. close the switch 4. set the variable resistor so that you get a less biased result- below 0.5 amps 5.

• Word count: 954
15. ## Aim: The aim of this experiment is to see how the length of a nichrome wire affects its resistance.

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If there are more collisions that means there is more resistance. Example: If there are 10 free electrons and have to go through 2 wires: a)10 cm and b)20 cm, there will be more resistance in wire b) as there will be more molecules in the electron's path in wire b) than in wire a). Aim: The aim of this experiment is to see how the length of a nichrome wire affects its resistance. Hypothesis: Resistance is caused by the collision of free electrons the fixed particles of the metal and its impurities therefore if the length of the wire is doubled; the electrons collide with twice as many molecules thereby doubling the resistance.

• Word count: 1048
16. ## Resistance of a wire

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TRIAL 1 Length (cm) Voltage (V) Current (A) Resistance (?) 100 6,4 7,2 0,888888889 90 6,3 7,7 0,818181818 80 6,2 8,7 0,712643678 70 6,3 10,2 0,617647059 60 6,1 11,5 0,530434783 50 6,1 13,7 0,445255474 40 6,15 16,8 0,366071429 30 5,83 21,8 0,267431193 20 5,71 29,3 0,194880546 TRIAL 2 Length (cm) Voltage (V) Current (A) Resistance (?) 100 6,4 7,3 0,876712329 90 6,4 8,1 0,790123457 80 6,67 9 0,741111111 70 6,28 9,9 0,634343434 60 6,32 11,9 0,531092437 50 6,28 14,2 0,442253521 40 6,12 17,3 0,353757225 30 6,09 22,4 0,271875 20 5,9 32,9 0,179331307 TRIAL 3 Length (cm)

• Word count: 874
17. ## What factors affect the resistance of Ni-Chrome wire?

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This was also show within my preliminary results as increased the amount of filament bulbs (in affect increasing the amount of wire) the resistance increased. Resistance: x = length of wire x = R = V/0.25 0.25 = Amps 2x = 2R = 2V/0.25 V = Volts 3x = 3R = 3V/0.25 R = resistance 4x = 4R = 4V/0.25 As you can see I think that as you double the length of wire the resistance also doubles, because of this the voltage must double as it is being divided by a constant and it must double so the resistance can double.

• Word count: 1967
18. ## Resistance of a Wire

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Results Plan The heading for my results table will be 'dial voltage', 'actual voltage', 'length of wire', 'current', and 'resistance'. To ensure a fair test I will make sure that the dependent variable will be the same through out the experiment. Safety I will assure that when I conduct my experiment, I will have a clear space between me and other students. I will use a heat proof mat to be the base of the wires so it will not heat up.

• Word count: 1183
19. ## Resistance of a Wire

4 star(s)

In a thin wire there is less space, but more resistance and in a long wire there is more space, yet less resistance. The flow of electrons: Hypothesis: Before I do my experiment I predict that the resistance in the wire will increase as the length of the wire increases. I also predict that if the resistance in the wire increases, then the thickness of the wire will decrease. My diagram of my circuit: For my first investigation task I will be doing a preliminary test to find out which are the best wires to use for my investigation.

• Word count: 1189
20. ## Investigation of Resistance in a Nichrome 32 Wire

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The collisions that occur produce heat energy which is caused by friction. I predict that if you double the length of the wire the resistance will also double. Fair Test: To make this a fair test I will keep certain variables the same, only changing the length of wire. The variables I will keep the same consist of the power supply so I don't send more power to the electrons to go around, and temperature so that it doesn't affect the resistance of the wire because increase of the temperature increases the resistance of the wire.

• Word count: 875
21. ## Q. How is resistance affected by changing the length of a piece of nichrome wire in a simple circuit?

4 star(s)

It is a very thin wire so it slows down the flow of electrons and takes energy away from the electrons as they struggle to get through it. The energy is then changed to heat and light. Current: The flow of electrons in a circuit is called the CURRENT. Current is measured using an ammeter. Current is measured in units called AMPS. Voltage: Voltage is the amount of energy that the electrons have. It is measured using a voltmeter. Voltage is measured in units called VOLTS.

• Word count: 762
22. ## To investigate How the Length of Wire affects its Resistance.

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Method 1. I will set up the apparatus as shown in the circuit. 2. I will get a wire of length 20cm and connect it to a wooden ruler. 3. The first crocodile clip will be connected to the wire at 0cm. 4. The second crocodile clip will be placed at the relevant length to which I am finding out the necessary information. 5. The power supply will be turned. 6. I will the read the readings from the Volt Meter and Ammeter.

• Word count: 1015
23. ## An investigation into the effect of temperature on a squash ball

4 star(s)

To judge how high the ball has bounced, I will be using my eyesight. Diagram Equipment list 4 different coloured squash balls Beaker Water bath 2, 1 meter rulers MDF Kettle Ice Thermometer Stopwatch Tongs I did a preliminary experiment to see if my method would work and if there were any problems with the way I will conduct my experiment. Preliminary Results Temperature (�C) Distanced Bounced (Cm) 90 81 40 68 0 20 Factors affecting my experiment * If I use different squash balls of different elasticity it will affect the bounciness of the ball.

• Word count: 1111
24. ## Ionization energies

4 star(s)

positive charge from the nucleus remains unchanged, however, there is less repulsion between the remaining electrons INVESTIGATION: Periodic trends in ionization energies First ionization energies as a function of atomic number * 1.Within each period (row) the ionization energy typically increases with atomic number * 2.Within each group (column) the ionization energy typically decreases with increasing atomic number HYPOTHESIS: * Investigation 1: As the effective charge increases, or as the distance of the electron from the nucleus decreases, the greater the attraction between the nucleus and the electron.

• Word count: 479