• 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
8. 8
8
9. 9
9
10. 10
10
11. 11
11

# To investigate the affect of wire width on electric current and resistance.

Extracts from this document...

Introduction

COURSE WORK PIECE 1: RESISTANCE HARRY HUDSON 10U 25/5/02 AIM: To investigate the affect of wire width on electric current and resistance. INTRODUCTION: What is electricity? Electricity is the phenomena resulting from the existence of charge. The units of charge are: one electron (negative charge) and one proton (positive charge). All normal atoms contain both of these particles, as well as neutrons (neutral charge). All solid metals contain atoms arranged in a regular structure. One or two electrons per atom are weakly attracted as they are further from the nucleus and are held in by a weaker force, and thus may move away from the atom and "wander" through the metal. The loss, or gain moveable electrons means the material has positive or negative charge. The main units used to measure electrical quantity are: ampere (unit of current), the coulomb (unit of charge), and the volt (measurement of electromotive force). What is current? Current is the term used to denote a flow of electric charge. This is known as ELECTRODYNAMICS, as we witness charge in motion. Electrons may flow through any material known as a conductor (all metals). The reason for this is the `free' electrons moving within the metals structure. In order for current to exist in a conductor, there must be an electromotive force (emf), or potential difference in charge at the two ends of the conductor; (the magnitude of potential difference (p.d) is measured in Volts). An emf such as, a battery with a positive and negative terminal supplies direct current, (flow in one constant direction). This is known as DC. In the presence of an emf these `free' electrons are attracted to the positive charge; thus creating a movement, or `flow' of electrons known as current. The reason for the movement of the electrons toward the positive charge is that `opposites attract'. What this means is that opposite charges are attracted to one another, in order to balance their charge so that they may become neutral. ...read more.

Middle

The coil of wire was unwound, and measured against the meter ruler accurately to ensure that he length of wire tested is as accurate as possible. For the 20cm, and 100cm tests of the same thickness, and material, the same wire was used to ensure as little variation in the wire as possible. The readings were taken as soon as the circuit was switched on, to ensure that the initial result was taken, and not the result after the circuit had heated up. We also tested the circuit before the length or wire was put in place to ensure that the circuit wasn't affected by any other variables. Results of preliminary test: Length (cm) Material Thickness Voltage (V) Amps (A) Resistance (Ohms) 100.0cm Copper Thin 1.37 1.82 0.753 20.0cm Thin 0.520 2.32 0.224 100.0cm Medium 0.820 2.28 0.360 20.0cm Medium 0.260 2.58 0.101 100.0cm Thick 0.540 2.56 0.211 20.0cm Thick 0.140 2.72 0.0515 100.0cm Constantan Thin 3.62 0.220 16.5 20.0cm Thin 2.80 0.810 3.46 100.0cm Medium 3.41 0.400 8.53 20.0cm Medium 2.27 1.24 1.83 100.0cm Thick 3.13 0.630 4.97 20.0cm Thick 1.67 1.68 0.994 All measurements given to three significant figures What is learnt? : This preliminary test is successful in showing us which values we should set the dependant variables at, and generally how to conduct the test successfully. We firstly see that the resistance of constantan is much greater than that of copper. Therefore a much smaller percentage of the total resistance is created by the other wires and equipment in the circuit. The resistance measured for constantan is therefore much more accurate. We can see this in the results, using the idea that length and resistance are proportional to judge accuracy. We also see that the thicker the wire the less resistance. It is undesirable to make the resistance low, as it will mean a greater percentage of each results will be error due to the other variables in the circuit. ...read more.

Conclusion

For example, my measurement of the ammeter of voltmeter may be inaccurate; the wire may not return to the same temperature in the cooling time allowed; the lengths of wire may not be totally precise. This is reflected in the variation, however slight in the repeated tests. In an ideal situation the repeated tests would show identical results for each test. If I were to repeat this experiment with greater time and facilities I would make the following changes to the procedure, to improve the accuracy of the experiment. To improve the accuracy of the wire measurement I would use pointers instead of crocodile clips, as they take up less area, this meaning the length of wire is more accurate. I would set up a computerized system to maintain temperature in the wire, and to measure more accurately the voltage and current in the wire when the system is at the same temperature. Low resistance equipment would be used so that a much smaller percentage of the resistance result is due to the equipment. To make the experiment more wide-ranging and valid to the hypothesis the following improvements could be made: another investigation could be carried out on different diameters of wire to see the proportionality in different diameters of wire; a different material could be used, which will have a different level of resistance and again test proportionality; a greater range of results may be taken to see if proportionality is maintained across such large ranges. I could also develop the investigation by looking at the other variables, and making other hypotheses from the scientific knowledge, thus extending my investigation and allowing the conclusion to be greater validated. These could include looking further at the affects of temperature and diameter by looking at many more diameters of wire, and the affects of different temperatures. Also, with a lower resistance equipment system, some other lower resistance materials may be investigated. These would all provide a more developed and accurate investigation, yet the experiment conducted was relevant to investigating the topic, and the hypothesis was successfully proven in the time given. ...read more.

The above preview is unformatted text

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)

For example, the random errors, such as, the misreading of the scale. The systematic error, such as the zero error i.e. an ammeter does not read zero when no current is flowing through it. However, these errors did not cause major errors in my readings but did account to a small possible change in gradients from graphs.

2. ## Resistance Aim: my main aim is to investigate the factors that affect the resistance ...

3 star(s)

If the cross-section of a wire is enlarged this means that the area on which the electrons move will be enlarged. Thus suggesting that there will be no clouds of electrons and atoms. The current can travel easily with nothing increasing the resistance.

1. ## Electromagnetism - investigating what effect increasing the number of turns in a coil on ...

Another way I could have improved my readings, the strength to a more accurate number, would to place an iron bar on a pair of scales then increase the strength of the electromagnet by adding more coils an investigate to see if the iron bar gets lighter.

2. ## Resistance of a Wire Investigation

The following diagram represents the absorption spectrum of pure chlorophylls in solution: An action spectrum, on the other hand, describes the efficiency of a particular molecule at achieving its purpose in absorbing light; this measurement shows what wavelengths of light the molecule can trap to conduct photosynthesis.

1. ## An in Investigation into the Resistance of a Wire.

Put the centre of the crocodile clip on the 20cm mark on the wire and then put the centre of the other crocodile clip on the 40cm mark on the wire. The wire that is not in between the two crocodile clips will get no electricity flowing through it because they are not part of the circuit.

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

LENGTH: Overall, my investigation involving length was a success because my results turned out exactly as I had predicted. In all my graphs for length, I got very few anomalies, and most of these were due to faulty equipment.

1. ## How does length and width affect resistance

Resistance opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. The circuit itself can resist the flow of particles if the wires are either very thin or very long.

2. ## The Efficiency of an Electric Motor.

1.6 26.7 0.248543689 0.374531835 6.636116505 10 50.69054307 2.56 1.4 33.4 0.190291262 0.299401198 6.355728155 10 57.33838446 1.96 1.2 46.7 0.139805825 0.214132762 6.528932039 10 53.16440638 1.44 1 69.5 0.097087379 0.143884892 6.747572816 10 48.20143885 1 0.8 112.68 0.062135922 0.088746894 7.001475728 10 42.8270323 0.64 0.5 360.76 0.024271845 0.027719259 8.75631068 10 14.20334849 0.25 0.4 593.72

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