• 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
7. 7
7

# I am conducting an experiment to find out how the length of wire affects resistance.

Extracts from this document...

Introduction

Science Coursework

Resistance

Introduction

I am conducting an experiment to find out how the length of wire affects resistance. The experiment I am conducting is passing an electric current through a wire made of constantan. I will take readings of the voltage and the current to find the resistance change when the length of the wire used is changed. I will be keeping the current and the voltage the same to obtain the results I want. The current will been kept unvaried by the use of a variable resistor. What I will be changing to find out about resistance is the length of the wire, 100cm – 10cm. I will work out the resistance of each experiment by use of ohms law, and I will repeat each length 3 times.

Method

To do the experiment I will first set up all the equipment (diagram below). The power pack will be set to 8volts and I will keep the current at a constant reading. To do this I will vary the variable resistor on each length change. I will connect all the equipment and turn on the electricity. I will then take a reading of the voltmeter. I will then change the length of the constantan wire by moving the crocodile clips down the wire to the length that is needed. I will then turn the power on to adjust the current flow.

Middle

The experiment will work by electricity passing through the constantan. The length of the constantan will change the amount of resistance there is. The longer and thinner the wire is the more resistance it has because of the amount positive ions the electrons will hit as they pass through the wire. Resistance is the property of any object or substance, resisting or opposing the flow of an electrical current. The amount of resistance in an electric circuit determines the amount of current flowing in the circuit at any voltage in the circuit. They can then show the amount of electrons passing through the wire.

The resistance is found by using ‘Ohms Law’. Ohms law, named after it discoverer, Georg Ohm (a German physicist). Ohms law states that the amount of current flowing through a conductor is directly proportional to the electromotive force applied between the ends of the conductor. Resistance is defined as the ratio of the electromotive force to current, this creates the formula R= V/I, where I is the current in amps, and V is the voltage. Ohms law works in both direct current (DC) and alternating current (AC), the circuit I am using though is DC.

The higher the voltage the more resistance that will occur due to the amount of electrons hitting the positive ions, if there are enough collisions the energy from this can make the wire become extremely hot and glow.

Resistance in wires can be shown by the diagram beneath

Conclusion

The factor in the resistance which takes into account the nature of the material is the resistivity . Although it is temperature dependent, it can be used at a given temperature to calculate the resistance of a wire of given geometry.

The inverse of resistivity is called conductivity. There are contexts where the use of conductivity is more convenient.

Electrical conductivity = σ = 1/ρ

## Resistivity Calculation

The electrical resistance of a wire would be expected to be greater for a longer wire, less for a wire of larger cross sectional area, and would be expected to depend upon the material out of which the wire is made (resistivity). Experimentally, the dependence upon these properties is a straightforward one for a wide range of conditions, and the resistance of a wire can be expressed as

Resistance = resistivity x length/area

For a wire of length L = m = ft
and area
A = cm^2
r = cm
and diameter
inches for common wire gauge comparison
with resistivity =
= x 10^ ohm meters
will have resistance
R = ohms.

Enter data and then click on the quantity you wish to calculate in the active formula above. Unspecified parameters will default to values typical of 10 meters of #12 copper wire. Upon changes, the values will not be forced to be consistent until you click on the quantity you wish to calculate.

 Standard wire gauges Table of resistivities

The factor in the resistance which takes into account the nature of the material is the resistivity . Although it is temperature dependent, it can be used at a given temperature to calculate the resistance of a wire of given geometry.

www.hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html

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. ## To investigate how the resistance, R, of a length of wire, l, changes with ...

4 star(s)

I could make this an improvement on my method if I was to do the experiment again. I could use a shorter wire than 1m, to increase the accuracy in the actual measuring of the wire, as it is easier to handle, than a longer wire which is harder to hold down and measure.

2. ## An Experiment To Find the Resistivity of a Wire

ACCURACY: - To keep this experiment as accurate as possible, I need to make sure the length of the wire is measured precisely from the inside edge of the crocodile clip, making sure that the wire is straight when I do this.

1. ## An experiment to find the resistivity of nichrome

This is because of the same reason that there are more Protons to collide with. Some metals have different resistances, this means that some metals such as copper are excellent conductors whilst other such as plastic are terrible. I will make this experiment fair by performing investigation on each variable

2. ## How the length of constantan wire affects the ressistance in a electrical circuit

However if longer wires do no not have a high resistance the plots on the graph would have been everywhere and it would have been a negative correlation. I have taken notice in most the graphs that when results of the voltmeter increases the current in the ammeter decreases.

1. ## Investigating how the length of a Wire affects its resistance.

My results are accurate enough because the graph shows a line of best fit in which most of the points sit on. The anomalous results are not really that far off and as explained before, this is because of the low current which also leads to better results.

2. ## To find out what happens to the efficiency of a motor as I change ...

Timing for lighter loads: Whilst testing lighter weights, the load was lifted too fast for an accurate measurement of time to be taken, using a simple stopwatch. Therefore the timing would have been inaccurate for some of the lighter weights tested.

1. ## Design an experiment to predict and test the output from a simple AC generator.

Wire Cost per 250g meters per kilogram cost per meter 1 �9.30 56 �0.66 2 �9.70 177 �0.22 3 �10.05 284 �0.14 4 �10.25 456 �0.09 5 �10.35 706 �0.06 6 �10.85 893 �0.05 7 �11.50 1820 �0.03 8 �12.15 3580 �0.01 9 �12.25 9195 �0.01 No using the viable generator combinations the cost can be calculated.

2. ## Find out how resistivity changes as the length of wire is changed, and to ...

atoms as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance. So to eliminate this 'extra' resistance I will have to turn the power pack off after a while to let the wire cool down.

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