Resistors are rated according to their maximum power dissipation. They usually absorb much less than a watt of electrical power and require little attention to their power rating.
I will place one crocodile clip at 0cm on the wire and the other at 5cm to complete the circuit. I will then turn the power pack on and record what voltmeter and ammeter readings. I will switch off the power pack, move the crocodile clip that was at 5cm up to 10cm, and switch on the power pack.
Again, I will record the voltmeter and ammeter readings and turn off the power pack. I will repeat this method every 5cm until I get up to cm, taking three readings from both the voltmeter and ammeter each time to ensure accuracy.
Apparatus Ensuring Accuracy To ensure accuracy I will record the voltage and the current three times every 5cm and take the average reading.
This will reduce the chance of false readings and will cancel out any anomalous results. I will also ensure that the wire does not heat up too much by confirming that I do not set the voltage too high on the power pack and by maintaining the same the voltage for every reading.
In addition, I will make sure I turn the power pack off after each reading. I will try to make this investigation as accurate as possible. Variables There are different variables that can be changed in this experiment; these are the independent variable. However, due to my line of enquiry, I will only change the length of the wire.
The variables I will control will be the type of wire resistivity and the cross-sectional area of the wire. I will also control, using the power pack, how many volts pass through the wire. Below is a table illustrating the effect of changing the variables see Table 2: Variables Safety I will ensure experimental safety by confirming that all the wires are connected properly and that none of the insulation on the wires is worn.
I will also ensure that there is a clear indication that the power is isolated by means of a switch and an L. I will stand up during the investigation to ensure that I do not injure myself if something breaks. Results Below is a table of my results Table 3.
I have taken three reading and have worked out the average, shown in red. This confirms the first part of my prediction: In addition, my prediction that doubling the length of the wire increases the resistance by a factor of two is correct see Table 4.
Graph Graphing these results shows a nearly straight line, illustrating a strong positive correlation between length and resistance, which is consistent with my prediction.
Discussion Overall, my results are very consistent with my predictions. Most of the data points were on, or very close to, the line of best fit. There are a few data points that are farther away from the line of best fit than the others, but they are still consistent with the general trend.
There are no anomalous results that I would consider to be far away from the line of best fit. There are possible sources of error that might have led to inconsistent results, such as a kink in the wire.
This would have prevented the area of the wire from remaining constant and would have affected my results.Independent variable; Dependent variable; Constant(s) Resistivity of a Wire. Name: _____ I. INTRODUCTION. The resistance of an electrical conductor depends on several factors.
Its physical shape is one factor. The type of conductor material is another, as might be expected. That is, two conductors with the same physical shape, but of. Introduction: It is proposed that there are factors that influence the extent to which metal relationship between length and resistance. Copper wire of nominal diameter resistance (dependent variable), due to their prevalence and common use.
The longer. How to measure resistance of a piece of wire? My suggestion for the temperature dependent part would be to measure the resistance of the wire with it in boiling water and ice water, for two easy reference points. share | cite | improve this answer.
answered Dec 16 '13 at The slope reveals that when the length of a wire is increase, the resistance would go up by an approximate measurement of Ω, which could be proven by the calculation of the graph where all the average was calculated from the average increments of each wire — (+++)÷4= 3 Students should come to understand that the resistance of a wire depends on its length, its cross sectional area, and the material out of which it is made.
With some students you could go further and introduce the concept of resistivity ρ, through the relationship R = ρ l / A where R = resistance, ρ = resistivity, l = length and A = cross-sectional area.
c Calculate the resistance of the lamp at its running temperature.
d Now, for several different values of p.d., measure the current through the lamp. Plot a graph of your results; this graph is known as the voltage-current characteristic of the lamp.