Resistance of a Wire
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Aim: The aim of this investigation is to find out how the length of a wire affects the current, voltage, and resistance of a wire.
Apparatus: To do the investigation I will need different pieces of equipment. I will need: A power pack
An ammeter
A voltmeter
5 wires – covered in plastic with crocodile clips at one end
A ruler
A long wire (approx. 100cm)
Sticky tape
Measuring:
Current: To measure the current, I will have to attach the wires to the ammeter, the power pack, the wire, and the ruler. The current (measured in amps) should automatically show up on the ammeter.
Voltage: To measure the voltage, I will use the same method but instead of using the ammeter, I will use a voltmeter
Resistance: To measure the resistance, you have to divide the current by the voltage. For example, if the current is 0.31 and the voltage is 0.60, the resistance would be 0.31 / 0.60 which would equal 1.93
Length: To measure the length of the wire, I will stick the wire to the ruler at both ends by using sticky tape. I will put crocodile clips on the wire, so each time I want to change the length; I release the clips and put them on the specific lengths.
Fair Testing: To keep the test fair, I must keep the power on the power pack the same all the way through the experiment. The things I will keep the same are:
Cross sectional area: This would affect the resistance as the thinner the wire, the more resistance.
Temperature of the wire: This would affect the wire as the hotter the wire, the more resistance (they gain more energy)
Material of the wire: The material could insulate the wire – making it warmer.
The thing I will change will be the length, as this is the topic that I am investigating.
Prediction: I predict that as the length of the wire increases, so does the resistance. I have predicted this because a longer wire has more currents and therefore there will be more