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How does changing the length of wire affect the resistance?

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Introduction

Resistance of a Wire

How does changing the length of wire affect the resistance?

Prediction

I think as the length of the wire increases the resistance increases. This is because there are more atoms for the electrons to collide into which slows down the flow of electrons

I think that as I double the length of wire the resistance will double because there are twice as many atoms to slow down the flow of electrons.

Length (cm)

Resistance (ohms)

5

0.5

50

3.5

100

6.8

This table is from an experiment using Nichrome wire with a 0.5mm diameter. It shows that the resistance doubles when the length of wire doubles because there are twice as many atoms that will slow down the flow of electrons in the wire.

Variables

  • Type/Material of wire
  • Diameter of wire
  • Length of wire
  • Current
  • Voltage

What To Do

  • Change the length of wire
  • Measure voltage across the wire at 0.2 and 0.4 amps to calculate resistance

Fair Test

Diameter (mm)

Resistance (ohms)

 0.02

25

0.04

6.4

0.08

1.8

1.00

0.2

This table is from preliminary data I collected.

...read more.

Middle

Method

  1. Collect apparatus
  2. Set up 20cm wire in circuit (as shown in diagram)
  3. Measure voltage across the wire at 0.2 and 0.4 amps
  4. Calculate resistance
  5. Repeat 2,3,4 with 40 60 80 and 100cm of constantan wire

Scientific Evidence

In a piece of wire atoms are arranged in a regular pattern called a lattice. The positive charges are concentrated in the nucleus and are unable to move. The negative charges (electrons) are freer to move. They normally flow haphazardly without direction. If a cell is connect the electrons flow to the positive terminal (+ve). This flow of charge creates an electric current

When the electrons in a current move in the circuit they collide into atoms in the wire. This causes a heating effect so in the experiment I will keep the current below 0.5 amps.

...read more.

Conclusion

If I had more time I would repeat the experiment twice and be more careful in taking my results and plotting my graphs taking temperature, voltage, length of wire, diameter of wire and resistance of the circuit into consideration a lot more as this will improve the reliability of the experiment. There are different results in both methods. This is because the Multimeter has its own power source and there will be less components putting resistance into the circuit, so the resistance should be less for Method 2 than Method 1 so Method 2 will have more accurate results.

...read more.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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