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The aim of this investigation is to find out how the resistance of a wire is affected by its lengths. I will do this by changing its lengths and working out each lengths potential difference and current.

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Introduction

EXPERIMENT TO FIND THE AFFECT THAT THE LENGTH OF A WIRE HAS ON ITS RESISTANCE

Introduction

The aim of this investigation is to find out how the resistance of a wire is affected by its lengths. I will do this by changing its lengths and working out each lengths potential difference and current. The reason that I am measuring the potential difference and the current of the circuit is because the formula for resistance is.

image00.png  or  image00.png  or  image03.png 
(resistance= ohms (
Ω), potential difference= volts (V), current= amperes (A))

Electricity is the movement of charged electrons inside an insulator and it is also a form of energy. The constant variables in this experiment will be:

  • The temperature: the hotter the inside of a metal the more active the electrons are and the more collisions they will make with the walls of the wires making it harder for the current to pass though
  • The material of the wire: different metals have different resistances and will give you unreliable results
  • The thickness of the wire: the thinner the wires are the less current can pass through it at one time.

The independent variable will be the length of the wires as we are trying to find out its affects on the resistance. The independent variable affects the dependant variable as in that when you change the independent variable the value of the dependant variable will change. The dependant variable in this case would be the resistance of the wires and it will change as the length of the wire changes.

Hypothesis: I think that the resistance of the wire will be higher when it is longer. This is because the electrons have further to travel than inside the smaller wires so it is harder for them. Therefore the electrons will use up the energy they obtained from the power source quicker and lowering the potential difference.

Method

Apparatus:

  • Nichrome (nickel-chromium alloy) resistant wires with changeable lengths
  • At least 5 conducting wires- to connect all the components
  • Voltmeter- to measure the potential difference
  • Ammeter- to measure the current
  • 2V battery- to provide sufficient voltage to push the electrons around the circuit. Converts AC to DC and steps it down to 2V from 230V
  • Access to mains electricity-to power the power source
...read more.

Middle

image10.png
1st

Length(cm)

Potential Difference (V)

Current (A)

Resistance (Ω)

10

0.469

0.25

1.88

20

0.631

0.16

3.94

30

0.973

0.09

 10.81

40

0.631

0.08

7.89

50

0.701

0.07

10.01

60

0.623

0.06

10.38

2nd

Length(cm)

Potential Difference (V)

Current (A)

Resistance

10

0.515

0.28

1.84

20

0.611

0.16

3.82

30

0.662

0.11

6.02

40

0.662

0.08

8.28

50

0.707

0.07

10.10

60

0.717

0.06

11.95

3rd

Length(cm)

...read more.

Conclusion

Conclusion

My hypothesis was proved true by my investigation as the resistance increased with the length of the wire. This means that the electrons found it harder to travel across longer lengths therefore needing more voltage to push it along. This means there is an increase in voltage and decrease in the current. The resistance equation mans that the resistance will keep getting higher with the length of the wire.

Evaluation

If I were to do this experiment again I would change a few aspects of it in order to obtain more reliable results and to make it a fairer test. I would keep the current the same although out the experiment by using a rheostat and adjusting the current to the same before every measurement is taken. I would keep the temperature of the room the same so that it does not have any effect on the electrons or the conducting wires. This will make it’s a fairer test because then you are only having one dependant variable which will make the outcome of the dependant variable more reliable.

...read more.

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