To investigate the factors which might affect the resistance of a component.
Electricity: Resistance
Part 1 - Planning
Aim: -
To investigate the factors which might affect the resistance of a component.
Background Information: -
An electric current is a flow off electrons. Electricity comes from the Greek word Electra, which was the Goddess of lightening. Metals have a tight giant atomic structure i.e. they are made up of very tightly packed atoms with free electrons. Such materials make excellent conductors of electricity. When a voltage is applied the electrons begin to flow in an orderly manner. An electric current is said to flow through the material. How large a current flow depends on how hard the supply is trying to push the current through the circuit and how hard the circuit resists having a current pushed through it. The current depends on the voltage and the resistance. The only time Ohm's law will not work is if the wire becomes very hot because the electricity is on for too long, so Ohm's law would be lost.
Preliminary Work
Aim: -
To investigate the factors which might affect the resistance of a component.
Apparatus: -
. Power Pack
2. Wires
3. Ammeter
4. Voltmeter
5. Crocodile Clips
6. Metal/Component (manganin)
7. Heat Resistant Board
Method: -
The ammeter will be attached to the component in series to the power pack, then the heat proof mat will be placed under the component in case of overheating and burning the table and then the voltmeter will be placed in parallel to the component to find the potential difference running from one end of the component to the other.
A
Ammeter
Resistor
V
Voltmeter
Safety: -
I am dealing with a resistor and electricity so I will wear goggles to protect my eyes from any sparks that generate from any mislaid part and will wear gloves, if I have access to a pair, to protect my hand from the resistor.
Chosen Variables: -
. Changing Voltage (1Volt, 2Volts, 3Volts, 4Volts and 5Volts)
Predictions: -
I predict that the higher the voltage the lesser the resistance because there is more push/potential difference when there is a higher voltage. e.g. If there is a big wall and one person tried to climb it, they won't be able to, so the wall is resisting a lot. On the other hand if there were thousands of people trying to climb it they will have more of a chance because they will build up until they could over it, so the wall isn't resisting a lot (change the people to electrons and the wall to the resistor). If I keep the electricity on for too long it will get hot and Ohm's law will be lost
Results: -
Test1
Test2
Voltage
(Volts)
Volts
(V1)
Amps
(I1)
Volts
(V2)
Amps
(I2)
0.02
0.01
0.02
0.01
2
0.50
0.24
0.05
0.24
3
.02
0.52
.11
0.57
4
.45
0.91
.51
0.97
5
2.04
.29
2.02
.28
Conclusion
Using the formula R=V/I I will work out the resistance
Test1
Test2
Voltage
(Volts)
Resistance
...
This is a preview of the whole essay
Results: -
Test1
Test2
Voltage
(Volts)
Volts
(V1)
Amps
(I1)
Volts
(V2)
Amps
(I2)
0.02
0.01
0.02
0.01
2
0.50
0.24
0.05
0.24
3
.02
0.52
.11
0.57
4
.45
0.91
.51
0.97
5
2.04
.29
2.02
.28
Conclusion
Using the formula R=V/I I will work out the resistance
Test1
Test2
Voltage
(Volts)
Resistance
(R1)
Resistance
(R2)
Average Resistance
2.00
2.00
2
2
2.08
2.08
2.08
3
.96
.95
.95
4
.59*
.59*
.59*
5
.58*
.57*
.57*
*= Anomalous
So upon looking at my figures I have concluded that no matter what the voltage is the resistance will stay the same.
So in my plan I will: -
Apparatus: -
. Power Pack
2. Wires
3. Ammeter
4. Voltmeter
5. Crocodile Clips
6. Metal/Component (manganin)
7. Heat Resistant Board
Method: -
The ammeter will be attached to the component in series to the power pack, then the heat proof mat will be placed under the component in case of overheating and burning the table and then the voltmeter will be placed in parallel to the component to find the potential difference running from one end of the component to the other.
A
Ammeter
Resistor
V
Voltmeter
Safety: -
I am dealing with a resistor and electricity so I will wear goggles to protect my eyes from any sparks that generate from any mislaid part and will wear gloves, if I have access to a pair, to protect my hand from the resistor.
Variables: -
. Changing Voltage (1V, 2V, 3V, 4V and 5Volts)
2. Changing Length (0.5m, 0.4m, 0.3m, 0.2m and 0.1meters)
3. Changing Thickness (1, 2, 3, 4 and 5 strands, when 1 strand is 0.045 cm in diameter so 2 will be 0.09 etc)
4. Changing Direction Of Current.
5. Types Of Wire/Resistors.
Chosen Variables: -
. Changing Length. (0.5m, 0.4m, 0.3m, 0.2m and 0.1meters)
2. Changing Thickness. (1, 2, 3, 4 and 5 strands, when 1 strand is 0.045 cm in diameter so 2 will be 0.09 etc)
3. Types Off Wire/Resistors (Secondary data)
Measurements: -
. Length (0.5m, 0.4m, 0.3m, 0.2m and 0.1meters)
2. Thickness (1, 2, 3, 4 and 5 strands, when 1 strand is 0.045 cm in diameter so 2 will be 0.09 etc)
3. Wire/Resistor Types (Copper, Manganin, Nickel Chrome and Constantan).
Fair Testing: -
I plan to do a fair test by keeping everything the same except the variable being tested.
Accuracy: -
I plan to do this experiment as accurate as possible by doing the experiment twice.
Predictions: -
. I predict that the shorter the resistor the lesser the resistance because the electron particles have a shorter distance to travel so they will not endure resistance as much as the electron particles that go through a longer resistor.
2. I predict that the thicker the wire/resistor the lesser the resistance because the electron particles have more room to travel.
3. I predict that the copper will have the least resistance and the manganin will have the most resistance because Copper is more dense, tightly packed and has freely moving free electrons than compared to any of the other resistors.
Part 2 - Obtaining Evidence
Safety: -
I am dealing with a resistor and electricity so I will wear goggles to protect my eyes from any sparks that generate from any mislaid part and will wear gloves, if I have access to a pair, to protect my hand from the resistor.
Apparatus: -
. Power Pack
2. Wires
3. Ammeter
4. Voltmeter
5. Crocodile Clips
6. Metal/Component (manganin)
7. Heat Resistant Board
Method: -
The ammeter will be attached to the component in series to the power pack, then the heat proof mat will be placed under the component in case of overheating and burning the table and then the voltmeter will be placed in parallel to the component to find the potential difference running from one end of the component to the other.
Variable 1: -
Constants - Volts (2volts) and Thickness (1strand)
Variable - Length (0.5m, 0.4m, 0.3m, 0.2m and 0.1meters)
Test1
Test2
Length
(meters)
Volts
(V1)
Amps
(I1)
Volts
(V2)
Amps
(I2)
0.5
0.43
0.31
0.42
0.31
0.4
0.39
0.38
0.38
0.37
0.3
0.33
0.43
0.35
0.45
0.2
0.26
0.50
0.26
0.49
0.1
0.20
0.53
0.23
0.56
Variable 2: -
Constant - Length (0.1m) and Volts (2volts)
Variable - Thickness (1, 2, 3, 4 and 5 strands, when 1 strand is 0.045 cm in diameter so 2 will be 0.09 etc)
Test1
Test2
Thickness
(strands)
Volts
(V1)
Amps
(I1)
Volts
(V2)
Amps
(I2)
0.20
0.53
0.23
0.56
2
0.09
0.63
0.10
0.68
3
0.08
0.70
0.09
0.73
4
0.05
0.76
0.06
0.73
5
0.04
0.75
0.04
0.76
After finding out the resistance of the two variables, which is going to be written down in Part 3, we got the classes results and wrote them down as secondary information and we had different types of resistors which were copper, manganin, nickel chrome and constantan.
Secondary Information
Constants - Volts (2volts) and Thickness (1strand)
Variable - Length
Length
(meters)
Copper
Manganin
Nickel Chrome
Constantan
0.1
0.016
0.39
0.48
0.21
0.2
0.023
0.52
.015
0.47
0.3
0.041
0.76
.71
0.80
0.4
0.043
.02
2.32
.185
0.5
0.056
.36
2.75
.35
Constant - Length (0.1m) and Volts (2volts)
Variable - Thickness
Thickness
(strands)
Copper
Manganin
Nickel Chrome
Constantan
0.016
0.39
.20
0.26
2
0.021
0.14
0.88
0.17
3
---------------
0.11
0.35
0.09
4
---------------
0.07
0.26
0.08
5
---------------
0.05
0.15
0.06
Part 3 - Analysis And Conclusion
Using the formula
I worked out the following
Variable 1
Constants - Volts (2volts) and Thickness (1strand)
Variable - Length (0.5m, 0.4m, 0.3m, 0.2m and 0.1meters)
Test1
Test2
Length
(meters)
Resistance
(R1)
Resistance
(R2)
Average Resistance(ohms)
0.5
.38
.35
.36
0.4
.02
.02
.02
0.3
0.76
0.77
0.76
0.2
0.52
0.35
0.52
0.1
0.37
0.41
0.39
Variable 2
Constant - Length (0.1m) and Volts (2volts)
Variable - Thickness (1, 2, 3, 4 and 5 strands, when 1 strand is 0.045 cm in diameter so 2 will be 0.09 etc)
Test1
Test2
Thickness
(Strands)
Resistance
(R1)
Resistance
(R2)
Average Resistance(ohms)
0.37
0.41
0.39
2
0.14
0.14
0.14
3
0.11
0.12
0.11
4
0.06
0.08
0.07
5
0.05
0.05
0.05
From our table of results it can be seen that, for the length being the variable, the resistance decreases as the length decreases.
This is because the current had a longer distance to travel than the smaller one. The results are directly proportional.
I saw, for the thickness variable, that the resistance decreases as the thickness increases. This is because the current has more room to travel. The results are indirectly proportional. Although I do not have enough evidence in the copper column in the variable "Thickness"
My prediction was right but for the metals being the variable I chose manganin to be the most resistive but it was the nickel chrome.
I can see that the density of copper is more than the density of iron and may possibly mean that density is linked to resistance. So the denser a metal the better it will conduct.
I did not have enough evidence for copper so I didn't plot the figures on the graph but upon looking on secondary sources I have seen that copper has a low resistance.
One of the best known conductors and one which is used extensively in industries and research is platinum. Its density is 21.37g/cm³. This very high density suggests a link between high density and low resistance.
Part 4 - Evaluation
I believe that I have a reasonable amount of data to make a conclusion but I still think I could extend the experiment by using different types of metals or use metals from group one of the periodic table and see if the lower you go in the periodic table the more resistive they become or visa versa. I think the plan is enough for others to understand if they feel the need to do the experiment again. I tried to be as accurate as possible. I cut the wires as accurately as possible and measured the readings as accurately as possible. The anomalous results could have occurred due to numerous things. I might have cut the wires to small or too big, the temperature of the room might have given the electrons more energy to move or I might have left the resistor resisting the electricity too long and the metal was burnt and I carried the experiment on with, you could say, a different resistor. This heating up of the resistor destroys Ohm's Law; the current being left on too long will cause the wire to expand destroying the Law. The atoms will then increasingly vibrate, the wire will then move apart, this will limit the movement of the electrons which will cause an invalidation of Ohms Law and this might have been the case for the anomalous results.
A further extension of my work could include an investigation involving the effect of density on resistance. I would use extremes of density e.g.:
. Titanium -4.50 g/cm
2. Germanium -5.46 g/cm
3. Zirconium -6.44 g/cm
4. Manganese -7.42 g/cm
5. Nickel -8.90 g/cm
6. Tungsten -19.10 g/cm
7. Gold -19.32 g/cm
8. Platinum -21.37 g/cm
