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Factors affecting the resistance of a wire.

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Introduction

Factors affecting the resistance of a wire

Introduction:

 Resistance is a force, which opposes the flow of an electric current around a circuit.

 Resistance is measured in Ohms. George Ohm discovered that a circuit sometimes resists the flow of electricity. He called this ‘RESISTANCE.’ He even came up with a rule for working out the resistance of a circuit, which was:

image00.png

R= V ÷ I

 V- Volts

 I- Current

 R- Resistance

Ohms law says the more resistance means more energy is needed for the current to pass through the wire. Resistance is a measure of how much energy is needed to push the current through something.

 Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance.

THE FOUR FACTORS THAT AFFECT THE RESISTNCE OF A WIRE ARE:

  1. LENGTH OF WIRE
  2. THICKNESS OF WIRE
  3. TEMPERATURE
  4. TYPE OF METAL

AIM:

To investigate how the length of a Nichrome wire can affect the resistance of a wire

PREDICTION:

In my opinion the longer the wire the more resistance there will be. I believe this because if the

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Middle

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METHOD:

I started of with the experiment by setting up the circuit as shown above. I had to be careful in connecting the circuit, because the voltmeter had to be placed in parallel and the ammeter, which had to be placed in series. The Nichrome wire was cut to just over 100cm so the crocodile clips could attach onto the wire, making the results more accurate. I stretched out the wire and sellotaped it to the ruler. I did this so I do not need to cut the wire every time, all I have to do is just move one of the crocodile clips to another length. The power supply is then switched on and put on 8 volts. I will then record the reading of the ammeter and put the results in a table. After this I will adjust the variable resistor to 7 volts, which would show up on the voltmeter, I will record the reading of the ammeter. I will once again adjust the variable resistor to 6 volts this time and record the reading.

I will repeat this for the other four lengths, which are as follows:

80cm

60cm

40cm

20cm

SAFETY:

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Conclusion

Further experiments I could do related to the resistance in a wire, would be to see whether the following factors would make a difference in the resistance of a wire : ( I have made a prediction for each factor from my own scientific knowledge on how I think the resistance would change in a wire for that particular factor )

Thickness of wire:

I think that if the thickness of the wire is increased the resistance will decrease. This is because of the increase in the space for the electrons to travel through. Due to this increased space between the atoms there should be less collisions.

Temperature:

I think that if the wire is heated up the atoms in the wire will start to vibrate because of their increase in energy. 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.

Type of metal:

If the material has a high number of atoms there will be high numbers of electrons causing a lower resistance because of the increase in the number of electrons. Also if the atoms in the material are closely packed then the electrons will have more frequent collisions and the resistance will increase

Jugbir Dhillon 10MD

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