Electrical currents are routinely harnessed and transmitted via interconnected wires. The purpose of this research is to identify factors commonly responsible for affecting the resistance of current, or flow of electricity, across a wire in an electrical circuit. Some factors will need to be identified and investigated prior to experimentation. A basic understanding of electrical circuits and resistance is required for successful completion of this project.
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In order to create an electric circuit, a path must be constructed to allow electrons to continuously move, or flow, across a medium. The movement of electrons is called the current. The medium used to conduct the electron transfer is called a conductor. The difference or potential difference in electrical charges in the circuit is called voltage. Voltage is the measure of the force between two pots. When electrons move through conductors they often encounter friction which is called resistance. As with voltage, resistance is a measurement between to points and does not have meaning outside of those two points. A conductor with low resistance is considered a good conductor and a conductor with high resistance is considered a bad conductor (http://science.howstuffworks.com/electricity.htm).
Because copper atoms have only one electron in their outer shell they tend to share electrons easily and allow an electrical charge to move through them with little resistance. Because of these properties copper is a good conductor (http://www.webelements.com).
Free electrons tend to move through conductors with some degree of friction, or opposition to motion. This opposition to motion is more properly called resistance. The amount of current in a circuit depends on the amount of voltage available to motivate the electrons, and also the amount of resistance in the circuit to oppose electron flow. Just like voltage, resistance is a quantity relative between two points. For this reason, the quantities of voltage and resistance are often stated as being between or across two points in a circuit. Resistance is the property of a conductor that inhibits or restricts the flow of electricity through it. Good conductors are associated with low resistance and high energy transference. Poor conductors are associated with low current and higher resistance (http://science.howstuffworks.com/electricity.htm).
Hypothesis:
The hypothesis of this experiment is: the resistance to an electrical current should increase in relation to the length of the conductor. The resistance should be proportionally higher for the 60cm length of wire than it is for a 10cm length of wire. Prior research indicates that the resistance of the 60cm length should be 6 times that of the 10cm length. Earlier studies indicate that resistance will increase with length because resistance is proportional to length (www.123HelpMe.com/view.asp?id=120694).
Project Plan/Problem Statement
Does the length of the conductor affect the flow of electricity? If it does, in what way? Resistance to an electrical current should increase in proportion to the length of the conductor. The resistance should be considerably higher for the 60cm length than it is for the 10cm length. Theoretically the resistance for the 60cm length should be 6 times that of the 10cm length. The reason for this was explained earlier. Resistances are just added together in a series circuit so having a long length of wire will just be the same as having 2 lengths of wire half the size. Resistance will increase with length. Resistance is proportional to length (www.123HelpMe.com/view.asp?id=120694). The mathematical formula for the relationship between two points, as described by Ohm’s Law, being directly proportional to the voltage across the points and inversely proportional to the resistance between them is expressed mathematically as: (http://science.howstuffworks.com/electricity.htm).
Or graphically as:
(http://science.howstuffworks.com/electricity.htm).
This science project will be used to test the length of an assortment of wires to determine how characteristic of length affects electrical conductivity. The electrons jump from atom to atom in the metal in response to the electric field in the circuit (http://science.howstuffworks.com/electricity.htm). Research tells us that copper has more free electrons than many other materials and should conduct electricity relatively freely (http://www.webelements.com/). The dependent variable for this project is the amount of resistance measured. The independent variable is the length of the copper wire used to conduct the electrical charge. The controlled variables for this project are constant room temperature, constant humidity, constant circuit, and a constant charge from a DC power pack.
The project plan is to test the current/resistance over different length of wires. This project is relevant to real world applications because if people have a better understanding of the factors that affect electricity conduction, enhancement can be made in electricity transmission to reduce loss of charge and increase preservation of electrical energy.
Literature Review/Other Experiments
Research has shown the conductivity of certain materials is:
Cu copper
use
2.15 nΩm
15.43 nΩm
16.78 nΩm
17.12 nΩm
17.25 nΩm
CRC (10-8 Ωm)
0.215
1.543
1.678
1.712
1.725
LNG (10-8 Ωm)
1.678
WEL (10-8 Ωm)
(293 K-298 K) 1.7
(http://www.webelements.com/)
Yamaguchi, T., Matsuoka, T., & Koda, S. (2007). A theoretical study on the frequency-dependent electric conductivity of electrolyte solutions. Journal of Chemical Physics, 127(23), 234501. doi:10.1063/1.2806289.
The accepting on the frequency-dependent electric accoutrement of electrolyte solutions proposed beat by Yamaguchi et al. [J. Chem. Phys. 127, 234501 (2007)] is affiliated to arbor the hydrodynamic alternation amidst ions. The accepting is activated to the aqueous band-aid of NaCl and the assimilation affirmation of the accoutrement agrees able with that angled by experiments. The abatement in the electric accoutrement is acceptance into the contributions of ion brace administering at acclimatized distances. The all-embracing ionic atmosphere plays a aloft role at the assimilation as low as 0.01 mol/kg, accepting the accession of the accent ion brace amphitheatre is important at 1 mol/kg. The acclimatized basal of cation is afflicted to be a abbreviating activity of assimilation as is empiric in experiments.
How Electricity Works, retrieved from http://science.howstuffworks.com/electricity.htm
The basal of electrons in motion in a abuttal’s is declared the current, and it’s abstinent in amps. The force allegation the electron alternating is declared the voltage and is abstinent in volts. The accumulated of electricity consumed were measured in watts.
“Investigation the Factors That Affect Resistance of a Conductor.” (21 Jul 2010) Retrieved from: (http://www.123HelpMe.com/view.asp?id=120694)
The factors that affect the transmission of electricity are: length of the wire- the greater the distance over the medium is the longer the electrons have to pass through and producing a higher possibility of impacts with other electrons; material used- the more closely packed the conductor (the nearer the electrons are) the more difficult it is for electrons to move through the conductor and so more crashes between particles, thus giving rise to a greater resistance; temperature- if the temperature of the cable is elevated then the atoms in the cable will begin to pulsate and that will augment the total number of impacts amid particles consequently rising the resistance; cross-sectional area- if the wires thickness is increased the resistance will decrease, this is because the electrons will have more space to move and that will make the probability of a collision with another electron is less likely.
Experimental Design Steps/Sequence of Events
This test set up should be able to assess the length of a wire for disparity in resistance of wire. Wires of differing lengths will be tested to verify that resistance is proportional to length. This will require testing different lengths of copper wire. For the experiment assorted wires from 10 cm to 60 cm will be tested using a current, a voltmeter and ammeter. The project will require an electrical circuit to test the resistance of a wire and an apparatus to connect differing sections of wire. To gauge the resistance of the wire conductor by means of Ohms Law, both an ammeter and a voltmeter will be used to check the electrical current. To achieve an average, the experiment will be conducted twice and then averaged for more accurate results. The power from the power source will be set at a current of 0.22 amps. Identical experiment steps will be utilized for wires of the following lengths: 10 cm, 20 cm, 30 cm, 40 cm, 50 cm, and 60 cm. The wire will be attached to the circuit in succession so that the current flows directly through it. Power will be supplied by a DC power pack that facilitates easy and accurate adjustments of power.
Steps:
Prepare circuit
Attach section of wire to be tested to circuit
Join one end of the ammeter to one end of the open circuit to guarantee that the whole current will be calculated.
Check the polarization of the ammeter’s ends that are connected to the circuit.
Turn on the power supply and increase the current to 0.22.
Check the reading from the voltmeter.
Check the reading from the ammeter.
Attach the 10 cm length of the copper wire to the circuit.
Apply 0.22 current to the circuit from the power source.
Check the reading from the voltmeter.
Record the reading from the voltmeter.
Check the reading from the ammeter.
Record the reading from the ammeter.
Calculate resistance.
Repeat steps 8-14 with 10cm, 20cm, 30cm, 40cm, 50cm, and 60cm lengths of copper wire.
The dependent variable for this project is the amount of current/resistance measured. The independent variable is the wire used to conduct the electrical charge. The controlled variables for this project are steady room temperature, steady humidity, and a steady charge in the form of a DC output from a DC power pack that will allow the power to be changed easily and accurately.
Reasoning
Copper is a widely recognized conductor that is extensively used in business and housing wiring for electricity. The greater the distance that the electrical charge has to travel then the greater chance of collisions with other electrons within the electrical current. In this experiment the length of an otherwise identical wire will be investigated to find how that factor affects resistance.
This experiment design method was chosen for its relative simplicity and ease of computing results. The reasoning behind this testing method was to prove fundamental factors of Ohm’ law and to test current laws in electrical conductivity.
Tools/Materials
Tools:
Ammeter
Votlmeter
Circuit
Power Source (DC Power Pack)
Materials:
Wire
10 cm copper wire
20 cm copper wire
30 cm copper wire
40 cm copper wire
50 cm copper wire
60 cm copper wire
Variables
The controlled variables, which must stay constant in this experiment to make it fair, are the output voltage from the power supply, which remains the same (0.22A) throughout measuring and the surrounding temperature should not rise or lower too much. The independent variable in this experiment is the length of the wire. The dependent variable is the output of current and resistance which are measured with a voltmeter and ammeter.
Threat Reduction to Internal Validity
To reduce the threat to internal validity a new wire is used for each subsequent test. Previously used wires are discarded after use to ensure that the wire has not been compromised in a previous test. All testing supplies and materials are kept clean and away from contamination. In order to reduce any inconsistency this experiment is repeated several times and several measurements are taken by meters which have previously been checked and determined to be free from defect.
Results
Experiment 1 Result:
Length
Experiment 1
Cm
I
V
10
0.22
0.08
20
0.22
0.14
30
0.22
0.23
40
0.22
0.32
50
0.22
0.4
60
0.22
0.47
Experiment 2 Result:
Length
Experiment 2
Cm
I
V
10
0.22
0.09
20
0.22
0.18
30
0.22
0.25
40
0.22
0.33
50
0.22
0.42
60
0.22
0.51
Average Result:
Length
Average
Cm
I
V
10
0.22
0.85
20
0.22
0.16
30
0.22
0.24
40
0.22
0.325
50
0.22
0.41
60
0.22
0.49
Conclusion
The resistance of the wire increases in proportion to length as predicted in the hypothesis. The results from this experiment have followed previous energy laws. The experiment proved that the resistance in 10cm of wire is roughly 50% of the resistance of 20 cm of wire, which is in turn roughly 50% of the resistance of 40 cm of wire. Additionally, the resistance of the 10cm wire is approximately 1/3 of the resistance of the 30cm wire. This is because 10 is 1/3 of 30.
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Confirmation of Hypothesis
Based in the results of this experiment the hypothesis is correct. This experiment proves that resistance increases in proportion to length. The evidence to support this is clearly shown in the graphs included above. As the length of the wire is increased, the resistance also increases directly proportional to the additional distance in length that the electricity had to travel.
Experimental Design as Key Factor
Experiments are generally conducted to prove or disprove a hypothesis, theory or an assumption. The legitimacy of any experiment is precisely affected by its design and implementation. Consideration of experimental design is particularly significant. If an experiments design is inconsistent the results and conclusions will be unsound and as a result will be unusable.
Replication
This project could be easily replicated using materials that cost less than $50. This is important because easily replicable results are not as likely to be impacted by accidental errors and if an experiment can be repeated under different circumstances by different people then it is most likely that the conclusions will remain the same and be accepted. Scientists are not likely to accept the results of a single experiment since the proposed hypothesis has to explain all experimental results and due to surrounding conditions, results could potentially vary,
Evaluation of Validity
This experiment is valid because it is easily reproducible, the data corresponds to scientific proofs, and most importantly the data is consistent through a variety of testing situations. This experiment would be easily confirmed by another scientist recreating the process. Further research is ongoing to develop a method of transmitting electricity with minimal resistance and loss of voltage.
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