How The Resistance Of A Wire Varies With Length.

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Physics Coursework - Grace Perry

How The Resistance Of A Wire Varies With Length.

Introduction:

                This experiment is to see how and if the length of a piece of wire effects resistance within a circuit. I already know that as the tempurature changes then so does the resistance and that if the wire is straight it decreases the amount of resistance opposed to when it is not straight and the resistance is increased. Electricity is a flow of charges in a circuit, a resistor is something that opposes the flow of an electrical current within the circuit. It is the electrons colliding with the atoms in the wire that causes the resistance. As the length of the wire increases the more atoms there will be, therfore more electrons, therefore more resistance. This then causes the charged particles to be pushed around the circuit more.

Resistance is meausured in Ohms from current and potential difference:

R=V/I

R= Resistance in Ohms

I= Current in Amps

V= Potential difference in Volts

Prediction:

                I predict that as the lenght of the wire is increased then the resistance will also increase. I think this because within the wire it is  made up of positive fixed ions with the negativly charged electrons, when the wire is connected into a circuit the charged electrons flow along the wire and become the current. When the negative electrons pass the positive fixed ions they then collide and then start to vibrate. This creates heat friction and causes the electrons to start moving more slowly and stop passing through the wire quite so quickly. The resistance has taken place and the current decreases.

                "When an electron passes through the wire, the electrons hit these atoms while making the journey from one end to the other giving opposition or resistance to the electrons. When this happens electrons move an electromotive force such as voltage, and in hitting these atoms, also creates friction of the electrons and atoms. When the wire is lengthend, the journey is considerably longer and the resistance changes" -                                                http://www.physlink.com/Education/AskExperts/ae218.cfm

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Equipment:

  • Leads x 8
  • Wire (1 metre)
  • Ampmeter
  • Voltmeter
  • Cell
  • Bulb
  • Meter Stick
  • Cellotape
  • Crocodile Cilps x 2

Preliminary Method:

                I set up the circuit using only one cell, an ammeter and a voltmeter all in series. Between the ammeter and the voltmeter I placed a bulb and the component, the wire. The wire was taped to a meter stick so to make sure that all the measurments were as accurate as possible to the nearest millmeter. I attached the wire to the leads by using two crocodile clips, one at each end. I then ...

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