I will be finding out the resistance of a wire in which its length is the variable. I will be investigating the process of how much the resistance increases due to the increase in the size of the resistor (nickel-chromium wire).

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Finding the resistance of a wire

Aim

For this experiment, I will be finding out the resistance of a wire in which its length is the variable. I will be investigating the process of how much the resistance increases due to the increase in the size of the resistor (nickel-chromium wire).

Investigation

Resistance is the property of an electrical conductor, to work against the flow of the current and change some of the electrical energy into heat. The quantity of resistance in an electric circuit determines the amount of current flowing in the circuit for any given voltage applied to the circuit, according to Ohm's law. The unit of resistance is the ohm and the amount of resistance that limits the passage of current to one ampere when a voltage of one volt is applied to it happens. The standard abbreviation for electric resistance is R and the symbol for ohms in electric circuits is the Greek letter omega, Ω. For certain electrical calculations, it is convenient to employ the reciprocal of resistance, 1/R, which is termed conductance, G. The unit of conductance is the mho (ohm spelled backwards) and the symbol is an inverted omega, W. To find the value of resistance, the equation

Resistance = Voltage / Current is used.

The resistance of an object is determined by a property of the substance of which it is made of, known as the resistivity and by the length and cross-sectional area of the object. Also, the temperature can determine the resistance of the resistor. At a given temperature, the resistance is proportional to the object's resistivity, length and inversely proportional to its cross-sectional area. Usually, a material's resistance increases with the rise in temperature as the voltage going across the wire has to avoid the resistor’s atoms more. This produces more energy causing plenty of heat.

The term resistance is also used when the flow of a fluid or heat is blocked. The forces of friction provide the resistance to the flow of a fluid in a pipe and insulation provides thermal resistance that reduces the flow of heat from a higher to a lower temperature. It is not just the resistor that causes resistance in the circuit, as any component in the circuit causes resistance. The 3 variables are the length, diameter of the wire, the material the resistor is made out of and the

temperature of the wire. The length of the wire will make a difference because there will be more atoms for the current to pass through so there will be more resistance in the wire. The diameter of the wire will make a difference as the thicker the wire, the easier the current will be able to pass through it, as there is more room within the wire. The material the resistor is made out of will also make a difference as if the wire has a high density, there will be more atoms in the wire causing high resistance, but if the wire has a low density, the atoms are less so there are so the is less resistance. The temperature will make a difference as if the temperature is high, there will be plenty of kinetic energy in the resistor and the atoms will be moving about. The current will find it hard to pass through the wire with atoms moving about so there will be more resistance. For the experiment, the variables except the length will be kept the same, as it will make it a fair test.

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If this experiment was to be done under perfect conditions, this is what the graph should look like if the graph was plotted with the resistance against the length of the wire.

From the above table, it is shown that if you double the length of the wire, the resistance also doubles. This also happens with the voltage. If you double the voltage, the resistance also doubles. It also shows that the voltage is the same as the resistance if the current is kept the same and if the length of the wire is proportional to the resistance ...

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