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Resistance Investigation. My aim in this investigation is to measure the amount of resistance in the different lengths of the wire.

Free essay example:

Physics coursework:

 Atom resistance

Aim:My aim in this investigation is to measure the amount of resistance in the different lengths of the wire. I will measure the different amounts of resistance by using the Ohms which is that the current =voltage / resistance:

image00.pngimage01.png

Prediction: My prediction was that the volt readings would remain similar measured using the voltmeter and the current would increase as the length of the wire would, thus increasing the amount of resistance in the increasing lengths of the wire.

Resistance

The current in a circuit can be changed according to the amount of voltage that is used to power the circuit. Another factor that is important is the amount of resistance that can affect the size of the current in the circuit. The resistance of an atom or an electron is when the flow of the electron in a circuit is altered or is being controlled from the loss of energy when the electron collides with the atoms in the path of the electron’s circuit. When the voltage of the battery or any other source of the power in a circuit pushes the electrons, the electrons then in the circuit collide with by passing electrons and also the other atoms, therefore the energy that electrons carry is transferred to the atoms and the other electrons that the collision occurs with gain the energy. The thermal energy from the heat of the collision is converted into kinetic energy which the atoms use to move and also collide with more electrons to increase the resistance.

What effects Resistance?

There are many variables that affect the flow of electrons in a current and the resistance of the electrons. One of them is the cross-sectional area of the wire because as there may be more space for the electrons to travel through the wire so the resistance of the electrons will be decreased as the flow of the current in the circuit is sped up. However if the cross-sectional area of the wire causes the flow of the current of the electrons to retard then the resistance of the flow of electrons would increase as the electrons have less space to travel through. Another variable that could affect the resistance is the material that the wire consists of. If the wire is made of a single element then the electrons moving through the atoms will only be able to collide with the atoms of that element which would increase the flow of the current and decrease the resistance of the electrons. However if the material of the wire is and alloy then the resistant of the electrons would certainly increase, as the second metal contaminating the first metal would allow more contact between the electrons and the atoms of the first and the second element, which increase the resistance and decrease the flow of the current. Also the third variable that can affect the resistance of the electrons is the temperature of the wire and the conditions around it. As temperature of the wire rises the resistance can increase because the atoms would be in faster motion because the thermal energy can be converted into kinetic energy which will decrease the flow of the current and will increase the resistance of the current because more collisions will occur.

What variables can I investigate?

One of the many variables that I can investigate is the length of the wire. The length of the wire means that if the wire is longer then the amount of resistance is increased because the electrons that travel through the wire would have to collide with more atoms. This would decrease the flow of the current. This would be an appropriate variable to consider to investigate in the investigation of the amount of resistance because the length of the wire can be measured easily in centimetres and also the amount energy left after a long wire can be tested to see if the flow of the current has been decreased or not. Also another variable that I could test is the temperature of the wire and the amount of resistance increased because the temperature that would increase could convert the thermal energy into kinetic energy for the atoms to vibrate more and then there would be more collisions which would decrease the flow of the current. This would be a suitable variable to investigate because the temperature will be measured in co in a room with controlled conditions (room temperature). The apparatus would be a thermometer and a Bunsen burner to use to heat the wire. Problems that could occur could be that the environmental conditions could not be suitable for the investigations.

Apparatus list:

  • Ammeter: Is used to measure the amount current flow through the conductor that is used (nickel chrome).
  • Voltmeter: The voltmeter is used to measure the amount of volts that the wire (conductor) contains.
  • Amp: The amp is used to power the circuit with electricity (2V is recommended).
  • Red and black wires: Used to connect the voltmeter, ammeter, amp and test piece to create a circuit.
  • Crocodile clips: These are used to clip the wires to the test piece (conductor).
  • Ruler: To measure the length of the wires (conductors) that will be used.
  • Pliers: These are used to cut the wire (conductor) to the suitable sizes required for the investigation.
  • Nickel chrome: This will be the wire (conductor/ test piece) used in the investigation.

Apparatus

Accuracy

Reliability

Ammeter

The ammeter is accurate because the degree of measurement is very accurate as it’s to 2 decimal places.

The ammeter was very reliable because the results that I had measured were matching the pattern of the changes of the current. However the ammeter could not have been reliable because the use of old equipment may have resulted in the incorrect outcomes.

Voltmeter

The voltmeter is accurate because the degree of measurement is very accurate as it’s to 2 decimal places.

The voltmeter was very reliable because the results that I had measured were matching the pattern of the volts being very similar. However the voltmeter could not have been reliable because the use of old equipment may have resulted in the incorrect outcomes.

Nickel Chrome

The nickel chrome was used for the required amounts. The constant use of the same piece of nickel chrome may mean that the wire would increase its temperature and this may result in the outcomes to be slightly different than they should be.

Them nickel chrome wire is very reliable because this wire is a suitable conductor and is an alloy which would mean that there would be some extra resistance to not allow the wire to over heat quickly.

Variables for the preliminary investigation:

After considering the possible variables that I could measure in the preliminary investigation, I decided to measure the resistance for different lengths of the nickel chrome wire which will then attached to a circuit to test the amount of resistant using ohms law.

My INDEPENDENT VARIABLE was: The length of the wires that was changed according to the required lengths.

My DEPENDANT VARIABLE was: The amount of resistance corresponding to the different lengths of the nickel chrome wires.

My CONTROLLED VARIABLE was: The material of the wire which was nickel chrome and the equipment used was the same throughout the investigation.

Preliminary method of the investigation:

  1. Firstly, the investigation began by setting up the apparatus in the correct order.
  2. The conductor needs to be cut to 10cm using the pliers.
  3. The conductor (nickel chrome) needs to be attached to the crocodile clips linking to the ammeter and the other one linking to the voltmeter.
  4. The dial on the amp needs to be set to 2V.
  5. Then record the results on an appropriately drawn table.
  6. Then repeat the investigation from step 2 till the end for different measurements of the wire (Conductor).
  7. The wire lengths will be 10cm, 15cm, 20cm, 25cm, and 30cm.

Apparatus diagram:

image02.png

Preliminary results:

Using Ohms law of resistance = volts / current the resistance could be measured.

Length of wire

(cm)

Material

Volts on the voltmeter (v)

Current

(A)

Resistance (Ω)

Fractional data

Decimal data (4dps)

10

Nickel chrome is used for all the lengths

2.3

1.20

23/12

1.9167

15

2.5

0.87

250/87

2.8736

20

2.4

0.69

240/69

3.4783

25

2.3

0.56

230/56

4.1071

30

2.2

0.48

220/48

4.5833

The results that were acquired from this preliminary investigation were viable and justified the general rule of resistance and my prediction, as the length of the wire increases the resistance will increase because there will be more atoms for the electrons to be able to collide with in the wire.

Definite investigation:

Taking many of the factors that can affect the investigation into consideration one of the major problems of this investigation was the temperature of the surround environment that day. The temperature of the surrounding environment could be a problem because at the time it was a very warm day. This could influence the investigation in a way such that the amount of resistance in each measurement would relatively increase because as the atoms are heated in the wire the thermal energy is converted into kinetic energy for the atoms to move and causing more friction between the passing electrons and the other atoms. This would increase the amount of resistance between the atom and the electrons. However the investigation was conducted all on the same day which would mean that even though there would be a higher temperature in the environment, it would all be consistent throughout and would therefore be eliminated as a predicament.

In the definite investigation the measurements of the wires in the investigation were also changed. The five measurements were changed from 10cm, 15cm, 20cm, 25cm, and 30cm to 10cm, 20cm, 30cm, 40cm, and 50cm. The five measurements were changed because they brought a significant changed to the out of the investigation. As the length of the measurements were increased the intervals between the values of the resistance would extensively increase because as the interval for the measurements is raised, consequently the amount of resistance will increase because there would a larger interval between the measurements and there would be a bigger difference between the resistance as there would be more atoms for the electrons to collide with in each measurement.

Definite results table:

(The mounts of volts from the amp/power pack was also increase from 2V to 3V to provide a greater push on the energy to let more energy be used to increase the intervals between the resistances of the five measurements)

Length of wire

(cm)

Material

Volts on the voltmeter (v)

Current

(A)

Resistance (Ω)

1st

2nd

3rd

Av

1st

2nd

3rd

Av

1st

2nd

3rd

Av

10

Nickel chrome is used for all the lengths

2.9

2.9

3.0

2.93

1.35

1.37

1.51

1.41

2.15

2.12

1.99

2.087

20

3.1

3.1

3.1

3.1

0.82

0.8

0.83

0.817

3.78

3.88

3.74

3.80

30

3.2

3.2

3.2

3.2

0.55

0.55

0.56

0.553

5.82

5.82

5.71

5.783

40

3.2

3.2

3.2

3.2

0.42

0.42

0.43

0.423

7.62

7.62

7.44

7.56

50

3.2

3.2

3.2

3.2

0.31

0.34

0.34

0.33

10.32

9.41

9.41

9.713

Discussion of results and graph analysis:

The results that I had found from this investigation were following the pattern that my aim of this investigation stated. As the length of the wire is increased the amount of resistance also increases. This is because the amount of extra atoms that added to the circuit will increase the amount of electron that will be free to move from the ions, this will also increase the collision between the moving electrons and the atoms, therefore more resistance will occur in the wire.

Analysing my graph:

Analysing my graph I have found my results to be following the pattern and that the intervals of the error bars were very small. This meant that the results were more accurate because the range of the results would mean that the line of best fit would be able to cross all the points through the error bars and it did. In terms of quantitative relationships between the variables and the results for resistance values, approximately as the length of the wire is doubled, the resistance is also doubled. This is presented in my results as the length of 10cm had an average of 2.087 ohms and the length for 20cm had and average of 3.8 ohms, the resistance for the 20cm is almost double the resistance for the10cm measurement. Also another example is the measurement for 20cm of wire had an average resistance of 3.8 ohms and the measurement for 40cm of wire had an average resistance of 7.56 ohms. This also qualifies as the results to be an example to prove the quantitative relationship because 3.8 would the exact half of 7.56, if the figure of 7.56 would be rounded to 2 decimal places, similar to 3.8 ohms.

Conclusion:

Concluding to my investigation, there were several factors that could have affected the investigation. Many of those factors were considered as issues. One of them was the temperature of the surround environment that day. The temperature of the surrounding environment could be a problem because at the time it was a very warm day/ hot day and the room wasn’t ventilated very well. This could have influenced the definite investigation on that day in a way such that the amount of resistance in each measurement would relatively increase. This would happen because as the atoms are heated in the wire the thermal energy is converted into kinetic energy for the atoms to move much faster (and gain more energy) and would have caused more friction between the passing electrons between the ions in the circuit and the other atoms. This would increase the amount of resistance between the atom and the electrons. However the investigation was conducted all on the same day which would mean that even though there would be a higher temperature in the environment, it would all be consistent throughout and would therefore be eliminated as an issue.

Aside from the issues, the pattern of the results was already discussed. The pattern will always follow, except for being an anomaly, the similar pattern as any other. As the length of the wire which is being used increases, consequently the amount of resistance will also increase corresponding to the relative increase of the wire length. Explaining this into further detail using quantitative relationships, the reason why the resistance increases is because as the length of the wire relatively increased from the last on, the amount of atoms and electrons will increase, therefore more collisions will occur. Into further detail, as the resistance follows a constant and a regular pattern, the resistance will double as the wire length of the wire correspondent to that results doubles. For example; the if the length of the wire is 20cm the resistance will be 3.8 ohms, therefore as the length of the can double to 40cm, the resistance is 7.56 ohm as represented in my investigation table. This means that this pattern and my data are very reliable, as 7.56 is only 0.04 ohms below the genuine mathematically calculated result, which is 7.6 ohms.

Further explaining the quantitative relationships; as the length of the wires double, the resistances in the correspondent wires also double. For example; if a 20cm had 5 million atoms, the resistance for a 40cm wire would be relatively double the resistance of the 20cm wire because as the amount of atoms double from 5 million (20cm) to 10 million (40cm), the amount of resistance would double because the electrons moving from several ions would have to collide with twice as much more atoms and the energy lost in each collision would double, therefore the resistance would double.

Diagram to explain the Quantitative relationship of the resistances:

Data reliability in explained conclusion:

The data that is recorded in my investigation is deemed to be viable and accurate. This is because I had judged the reliability of the data according to the error bars that were drawn in the graph. As presented in the graph the error bars have a very small range, therefore they are more accurate as the data interval is smaller. Also as the range of the data is much smaller and accurate the errors bars don’t overlap, and this means that there is a real difference between the results and this would mean the variations of results in each repeat of the investigation are closer to the average.

Considering the factors that could affect the investigation, such as the temperature, there could have been anomalies in the investigation because of the influence of the temperature or the quality of the apparatus. In the first measurement of the investigation for 50cm I had recorded the resistance as 10.32, while the other two repeats were both 9.41. The measurement for 10.32 may have been an anomaly because it was 0.91 ohms larger than the other results. This could have been because of the apparatus that was being used in the investigation. The apparatus could have been faulty, then this would state that the rest other results may be reliable, however there could have been other outliers in the investigation, as the same equipment was used throughout the whole investigation.

Evaluation:

Evaluating to this investigation, what the main aim for this investigation was is achieved, as the aim was to calculate the amount of resistance of five different measurements in the intervals of ten starting from 10, using the voltage and the current to calculate the resistance in the wires. As presented by the data the procedure of the investigation was very reliable and was conducted very well as one of the factors was the temperature of the wire. One of the ways that I had avoided this issue was by using separate nickel chrome wires for each of the measurements. This would mean that the wires that were being used in the investigation wouldn’t over heat and therefore their atoms wouldn’t gain extra energy to create extra vibration, which would then mean that the investigation wouldn’t have been jeopardised.

There were some factors that could have affected the investigation’s reliability negatively. One of them was the temperature of the surrounding environment. The temperature of the surrounding environment could be a problem because at the time it was a very warm day/ hot day and the room wasn’t ventilated very well. This could have influenced the definite investigation on that day in a way such that the amount of resistance in each measurement would relatively increase. This would happen because as the atoms are heated in the wire the thermal energy is converted into kinetic energy for the atoms to move much faster (and gain more energy) and would have caused more friction between the passing electrons between the ions in the circuit and the other atoms. This would increase the amount of resistance between the atom and the electrons. As this was a natural problem and the temperature of that day couldn’t be changed there was nothing that could have been done at that time to eliminate this factor to increase the reliability of this investigation.

Also another factor which was a problem was the quality of the apparatus. The apparatus of the preliminary investigation was faulty; consequently the apparatus could have had very minor unnoticeable faults that couldn’t have been distinguished from natural variation of results and being an anomaly due to the faulty apparatus. What could have been done about the faulty equipment could have been to improve the quality of the equipment by using knew pieces of instruments and apparatus.

Both of these factors could have created an anomaly in the data because as the misuse or abuse of the apparatus could have caused a malfunction in the equipment, therefore the incorrect results would have been recorded, for example the measurement of 10.32 ohms for the length of 50cm. Also the temperature could change the speed of the amount of collisions between the electrons and passing ions, which would have increased the resistance. This problem could have been solved, if at the there was an available temperature controlled room

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