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How the area of a wire affects the resistance in a circuit

Extracts from this document...

Introduction

Alex

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Middle

 How the area of a wire affects the resistance in a circuit

Planning

Background Physics:

What is resistance?

Electricity is conducted through a conductor. Resistance is the word used to describe the opposition between forces. The more free electrons there are, the better the conduction and the worse the resistance is. The more atoms vibrate, the more resistance there is. The free electrons are given energy, as a result they move and collide with the surrounding electrons. This happen throughout the whole wire. This is how the electricity is conducted. Resistance is the result of energy loss in form of heat.

How do we measure it?

V=I/R  V=Voltage I =Current R=Resistance

Ohm’s Law

This law states that the current through a metallic conductor (wire) at a constant temperature is proportional to the potential difference (Voltage). Therefore the Voltage and Current is constant. If the resistance increases the temperature increases, so it stays constant. At higher temperatures the particles move more quickly, increasing the collision of the free electrons.

Possible Input Variables

Wire area

Wire thickness

Wire length

Applied voltage

Material

Taught connections

Cross-sectional shape

Insulated

Density of wire

Coiled or not

Temperature

Preliminary Experiments

Easy to measure?

Easy to change

Wire area

Wire thickness

X

X

Wire length

Applied voltage

Material

X

Taught connections

X

X

Cross-sectional shape

X

X

Insulated

X

Density of wire

X

Coiled or not

Temperature

...read more.

Conclusion

My Area graph looks like a y =1/X graph

image01.png

X

Y

1

1

2

0.5

3

0.333

4

0.25

To reassure this I have plotted an average 1/Area. If it is correct then I should  get a straight line. When I plotted the graph I had a straight line.

This tells me that the average is proportional to 1/Area i.e. Rave α 1/Area.

The slope is: y/x= 10.5/16= 0.66 Ω/m²

I am ignoring the offset on my 1/Area graph

This experiment shows me that resistance is definitely affected by the area of the wire. Looking at my background physics it has worked out like resistors on a parallel circuit. When attaching another wire to the experiment it acts like adding another  parallel resistor in a parallel circuit.  So if the area of the wire increases the resistance decreases. Also I have learned if the voltage goes down the resistance goes up

Evaluation

I found this experiment easy to do. I had no anomalies on my graph. This means that the points I have plotted are all in a acceptable arrangement. There were no experimental caused by a faulty connection. There were no safety hazards and the experiment was safe to do.  

...read more.

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