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# Investigate the factors that affect the resistance of a wire.

Extracts from this document...

Introduction

Physics coursework assessment.

Investigate the factors that affect the resistance of a wire.

1.  Scientific evidence, plan and prediction.

Resistance is the property of any object or substance of resisting or opposing the flow of an electrical current. This can be shown easier in a diagram: -

Current is: -

A flow of electrical charge carriers, usually electrons or electron-deficient atoms.

Voltage is: -

Is an expression for electric potential or potential difference.

OHM’S LAW

The current in a circuit is proportional to the voltage.

V = I x R      or      R = V                    or      I = V

I                          R

Resistance ( R )= p.d. across the wire ( V )

Current through the wire ( I )

V = voltage or potential difference in volts (V)

Middle

There are four factors that effect resistance.

Wire length: If the length of the wire is increased then the resistance will increase as the electrons will have a longer distance to travel through the wire and so more collisions will occur. This length increase will be proportional to the resistance increase.

Thickness: (cross-section area) If the wires width is increased the resistance will decrease. This is because of the increase of space allows the electrons to travel through easily and not collide. This increase in space between

the atoms means there should be fewer collisions.

Temperature: If the wire is heated up the atoms in the wire will start to vibrate because of the increase in energy. This causes more collisions between the electrons and the atoms.

Conclusion

igate the length of the wire.

In this experiment I will use:-

A power pack,

Bare constantan resistance wire (0.704),

A ruler,

Voltmeter,

an ammeter and,

2 crocodile clips to clip to either end of the wire.

You set up the circuit like this

Prediction

I predict that as the length of the wire increases the resistance will increase. This happens because the electrons will have a longer distance to travel through the wire and so more collisions will occur increasing the resistance.

Method

1.  Set up the circuit.

2.  Vary the dial on the power pack to get 0.3, 0.6, 1.0, and 1.5 on the ammeter and calculate the resistance.

3.  Repeat this at 10,20,30,40,50,60,70,80cms.

4.  Each time take the reading from the voltmeter and put on a table of results.

5.    Plot graphs for each set of results and a graph of the averages.

Results

10cm

20cm

30cm

40cm

50cm

60cm

70cm

80cm

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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