• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5
6. 6
6

# Investigate if the length and cross-sectional area affects resistance through a circuit.

Extracts from this document...

Introduction

PLAN FOR SCIENCE INVESTIGATION

## Aim:

My aim is to investigate if the length and cross-sectional area affects resistance through a circuit.

## Back ground scientific knowledge

What resistance is:

## To find the resistance of something we use the following formula:  V

Resistance = V                                                    I    R

#### I

Resistance is the ratio of potential difference.

As long as I × V and the resistance is constant, and the conductor obeys Ohms Law.  The voltage increases, as long as they increase at the same rate.

V

Constant

Temperature

I

Ohm’s law

Ohm’s law means that if the voltage is doubled, the current will be doubled. The formula for ohm’s law is the following:

V = I × R

This defines resistance, for Ohmic conductors the resistance is constant, and ohm’s law of proportionality holds.

What causes resistance is:

Resistance of a straight wire depends on:

1. It’s length- the resistance increases with the increasing length.
2. It’s thickness- the resistance is greater for thinner wires.
3. It’s material- good conductors have a lower resistance.

Middle

= Atoms vibrating

Electrons move around the lattice in a random movement, with different speeds and different directions.  They collide with each

Other and the atoms. As they hit into each other the movement is passed on and the vibration increases.  More collisions mean greater resistance and more energy exchange.

Variables

Length: The longer the piece of wire the more collisions there is, and therefore the greater the resistance for a given current.

Cross-sectional area: The narrower the conductor the greater the number of collisions for a given current.

Temperature: the higher the temperature the more vibration in the lattice, the more collisions for a given current.

Material: the material from which the wire is made.

Resistively: resistively is related to the number of factors, which

affect resistance:

• Number of free electrons
• Crystallinity in lattice

By reducing crystallinity, it quickens up the flow of electrons and increases collisions, for a given current.

Preliminary work

To help me understand more I have decided to do some preliminary work.  This will help me to research the experiment and explore faults in the experiment.

Conclusion

Conclusion

My graphs show that there is a relationship between my voltage and current.  I can see that my results form a straight-line graph, which shows that my results are correct. I can also say that my choice of equipment was correct as I obtained good results. I controlled the variables well throughout the experiment, particularly the temperature.  I did this by switching off the D.C power supply after each result, to keep the temperature down.  I have discovered that the smaller the CSA of the constantan wires, the lower the resistance. I have observed the relationship between voltage, current, and gradient.  The higher the gradient the greater the resistance, which means there must be an increasing voltage and current.  My graph shows that it obeys ohms law, and did not over heat.  Overall it showed to be a success because I obtained a straight-line graph.

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

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related GCSE Electricity and Magnetism essays

1. ## Investigate how the cross section of a wire affects the resistance in a circuit.

= V I From previous research, it has been discovered that a voltage/current graph for a wire, is a straight line through the origin. This means that the voltage across the wire is proportional to the current through it. Therefore if the voltage would double, the current will double.

2. ## How the Resistance of a Wire is affected by Cross-Sectional Area

* A Voltmeter- used to measure voltage. Connected in parallel. * Two different thicknesses of Nichrome wire- used to experiment on. * Two different thicknesses of Constantan wire- used to experiment on. * Meter ruler- used to keep the wire to 20 cm long.

1. ## To investigate how the length (mm) and the cross-sectional (mm2) area of a wire ...

that drift to the positive end and by absorbing electrons at the positive end. Although the two terminals (positive and negative) are constantly receiving and sending out electrons, the electrons themselves do not move very quickly. It is the current that flows through the electrons at the speed of light

2. ## How does the length and cross-sectional area of a wire affect resistance

Due to this the length increase should be proportional to the resistance increase. Figure 2 The wire above is half the length of the wire in figure 2 and so there should be half the number of collisions between the electrons and the atoms.

1. ## Physical - Circuit

2.27 0.36 25 0.9 2.34 0.39 30 1 2.37 0.43 As the table shows above, the resistance of the length 5cm and 10cm were equal, and then it suddenly decreases. This shows there's an error; I think it happened because we didn't set our circuit in the correct positon.

2. ## Investigating How the Cross-Sectional Area of a Conductor Affects the Resistance of Current Passing ...

Use this method to test six lengths of wire with differing cross sectional area. I will make sure that my test is fair by using the same length of wire in at each stage of the experiment. I will control the voltage through the circuit using a variable rheostat.

1. ## The aim of this investigation is to find out the cross-sectional area of a ...

This therefore should make the experiment a fair test. The length of the wire may change a bit due to human error; we cannot measure the length of the wire exactly the same each time. All we can do is try to be as accurate as possible when measuring the length.

2. ## Investigating Resistance&amp;amp;#150; To investigate if and how a wires length affects the resistance.

to the voltage across it, the material is said to be "ohmic", or to obey Ohm's law. A microscopic view suggests that this proportionality comes from the fact that an applied electric field superimposes a small drift velocity on the free electrons in a metal.

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to