HYPOTHESIS
The reason why I think this will happen is because in the wire the electrons will be able to get passed more freely. This is shown in the diagram below.
Electrons Atoms
(I) Current is what flows on a wire or a conductor like water flowing down a river. Current flows from points of high voltage to points of low voltage on the surface of a conductor. Current is measured in (A) Amperes or Amps.
(V) Voltage is the difference in electrical potential between two points in a circuit. It’s the push or pressure behind current flow and through a circuit, and is measured in volts (V).
(R) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistor allows a small amount of flow. Resistance is measured in ohms. As the resistance is increased so will the current.
V
I
The graph shows how resistance and current increase
BACKGROUND KNOWLEDGE
Current is the flow of electrons around the circuit. Voltage is the driving force, which pushes the current around this is like electrical pressure. Resistance is anything in the circuit, which slows the flow down. If the voltage is trying to push the current round the circuit, and the resistance is opposing it, the relative sizes of the voltage and the resistance decide how the current will be:
IF YOU INCREASE THE VOLTAGE → THEN MORE CURRENT WILL FLOW.
IF YOU INCREASE THE RESISTANCE → THEN THE LESS CURRENT WILL FLOW.
The electric flow of current in a circuit is simply negatively charged electrons. The electrons flow from the negative terminal to the positive terminal. The Ammeter measures the current (in amps) flowing through the component. The ammeter must be placed in series. It can be put anywhere in the main series circuit, but never in parallel like the voltmeter.
The voltmeter measures the voltage (in volts) across the component. It must be placed in parallel around the component, NOT around the variable resistor or the battery. The proper name for voltage is ‘potential difference’ or ‘Pd’. I know that if there are more atoms then there will be more collisions with the electrons and the atoms. This means that the resistance would be high and the current would be low.
Substances, which allow an electric current to flow through them, are called conductors. Those, which do not, are called insulators. Metals behave as conductors because of their structure.
Some conductors are better than others. Copper is a better conductor than iron. When the electrons are moving through the metal structure they bump into the metal irons and this causes resistance to the electron flow or current.
OHMS LAW:
The German scientist George Simon Ohm (1787-1854) made an important discovery about resistance. He studied the relationship between the amount of current that flowed through a wire (the amperage) and the amount of electromotive force that drove that current (the voltage). In the substance he tested, he found that if he doubled the voltage, the current would be cut in half. Resistance remained the same when the voltage and current flow increased or decreased.
This is called ohms law. Ohms law defies the relationship between Power (P), Voltage (V), Current (I) and Resistance (R). One ohm is the resistance value through which one volt will maintain a current of one amp/ampere.
The formula shows the relationship between Power, Voltage, Current and Resistance.
To measure the resistance the formula below shows how it is measured:
Resistance = Voltage (volts)
Ohm’s Current (amps)
SAFETY
To make the experiment safe I will make sure that I am reasonably away from the electricity (when the appliances are switched on). I can also make sure that my hands and the surface are not wet. Therefore I would make sure that the appliances are not near any water. I will also make sure that my experiment is not being done on the edge of the table because this could then make the experiment fall off the table.
FAIR TEST
To keep the experiment fair, I will make sure that I will keep the following factors constant. They are the Power Pack, the Voltmeter, the same 1-meter Ruler, the same crocodile clips and the Ammeter. I will also make sure that the lengths of the wires are accurately measured. I would also keep the circuit the same.
EQUIPMENT
- 1 Long wire,
- 2 Short wires,
- 1m Ruler
- Ammeter,
- Voltmeter,
- Power Pack,
- Crocodile clips.
PLAN
To begin with I will gather the apparatus, which is needed for the experiment. I will then set-up the experiment. After doing so I will then test out the different length. The lengths will be measured as, 10cm, 20cm, 30cm, and 40cm and so on up to 100cm. the reason why I am doing these lengths is because then I would achieve better results, this is only what I think personally.
After that I will carry out the experiment twice so that I can make sure the results are accurate and fair. Then I will record my results in my table to see what the resistance, current and voltage are and work out the average. I will also read my measurements to 2 decimal places. I will measure the my results in Amp’s which is the measurement for Current, Volt’s which is the measurement for Voltage and Ohm’s which I the measurement for Resistance.
Finally I will gather my results and plot them on to graph paper to show any patterns between the lengths of the wires.
Here is an example of how my results table would look like:
DIAGRAM
The diagram below shows how the experiment will be like
METHOD
To begin this experiment; I first started off by collecting by equipment from the trolley. There will be two sets of results to ensure accuracy and an average set of results will be worked out. The crocodile clips were then connected to the each ends of the wires. I connected the wires to the Ammeter, Voltmeter and the Power Pack and the 1-meter Ruler (this is shown in the diagram).
At this stage of the experiment the resistance was measured at 10 different intervals. At each stage the length of the wire was increased by 10cm until it reached up to 100cm. This was done whilst moving if across the 1-metre ruler during the experiment.
The experiment will then be carried out again for the second set of results. From this a table can be provided to show the average readings as well as plotting graphs.
RESULTS
The table shows the current and resistance
The results above show how I calculated the average by adding the 1st and 2nd set of results and dividing it by 2. The experiment was done twice to gain accuracy, precise and more reliable results. From these set of results I can see that the longer the wire the higher the resistance and the lower the current. My prediction stated this.
ANALYSIS
In this experiment I know what I will receive as results, for this experiment as my whole class and myself done this experiment in year 9, so I am sure that if this experiment has the sort of same results as I gathered in year 9, it means that this experiment is accurate.
By looking at the results I can tell that the longer the wire the more resistance is present. I think that these are accurate because I did the experiment twice to determine the average values.
By doing this I also wanted to make sure that the results were precise. From looking at the results tables, I did find a pattern. This was from looking at the 20cm length of wire. The current was high and the resistance was low. However at 40cm the current was lower and the resistance was just a bit higher, so this means that as my length doubled the current decreased and the resistance increased.
This pattern was shown throughout the experiment. My prediction stated this factor that the longer the wire the resistance will be increased too. This showed in my result table. An example of this is shown in the table below:
The table shows the current and resistance
The above table shows what my prediction stated. In this investigation I found out relationships between the resistance and the current, this was that when the length increased the current decreased, the resistance increased. However the results may have been slightly inaccurate because during the experiment as the wires became hot. This could be due to human error or the equipment may have been faulty.
CONCLUSION
At the beginning of this investigation, I had predicted that the longer the wire the more resistance would be present. The results obtained during the experiment showed that they were accurate. There were no incorrect results because I think that my results were good enough to get these accurate and precise results. This also means that there would have been fewer collisions between the atoms and the electrons.
The electrons moving in the object hits the atoms and gives them energy then heats the object. The pressure had to work against the resistance. The electric current will only flow if there are charges, which can move freely, but electrons flow the opposite way.
Current is what flows on a wire or a conductor like water flowing down a river. Current flows from points of high voltage to points of low voltage on the surface of a conductor. Current is measured in (A) Amperes or Amps. (V) Voltage is the difference in electrical potential between two points in a circuit. It’s the push or pressure behind current flow and through a circuit, and is measured in volts (V).
(R) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistor allows a small amount of flow. Resistance is measured in ohms.
IMROVEMENTS
If I were to do this investigation again, the following improvements would be made:
- To solve any problems of human error, I could have used colleagues to help assist me with the experiment to ensure minimum error.
- Get a bigger comparison, by getting more results.
- Use different metals and different thickness of wires. This is because resistance can be differed by this.
EVALUATION
The procedure, which I carried out, was fair because I used the same apparatus for the experiment. This was showed in the results by the accuracy and reliable results. The results gathered were accurate because a average set of results was calculated and that my results were recorded at 2 decimal places. I also knew what kind of results I would expect from the experiment as I did this experiment in year 9.
I think that the results I had taken was not enough to say what I found was true, because if I had taken the length into more consideration for e.g. going up in 5’s, I would have gathered more and precise results. I also think that considering that I done this experiment in year 9 we could have thought, that we would achieve more precise results if I had gone up in 5’s.
From this I think I could have got even more precise results. The anomalous results that I found was on graph’s 4 - 10 the reason why I think this is because of the variables that are the thickness of the wire, the materials of the wire, the length o the wire and the temperature. I think that I could say that my method is reliable and that someone off the street can follow my method.
In order to extend this work I could have carried out the same experiment but change the lengths of the wires from 10, 20, 30- 100cms. To 5, 10, 15, 20-100cms (so basically increasing in 5cm at each interval). I could also improve this and extend this by using different thickness of wires. Also by using different metal materials. This is because different metals are either poor conductors or good conductors. On the whole I would consider that my experiment was good enough to which a conclusion good be drawn.
BIBLIOGRAPHY
- THE ESSENTIALS OF GCSE PHYSICS
- Lonsdale Science Revision Guide
- Author: Mary James
- COLLINS STUDY & REVISION GUIDE