Investigation Of Four Resistors Connected In Series

And In Parallel. Essay, Research Paper


of four resistors connected in series and in parallel. Background:Resistance is what opposes the flow of electrons in an

electric current through a conductor. Resistors are conductors that have a high

resistance. A conductor is the material through which an electrical current

flows. ? The Resistance, (R) of any conductor is given by the

equationR=V/I ??????????? where

V=p.d. across the conductor ??????????? ?????????? I=currentaccording to Ohm?s Law ? V=I/RAim: The aim of this experiment is to investigate how different

amounts of resistors in series and in parallel affects the resistance of an

electrical circuit, and what effects they have on the current.Variables:???????? number

of resistors ??????????????????????? series/parallelConstants:??????? voltage ??????????????????????? length/materials

of wires ??????????????????????? type/resistance

of resistors ??????????????????????? I will use a voltage of five

volts in each experiment. I have chosen this voltage so that the circuit does

not heat up too much.Method: I will have to set up circuits as in the diagrams below to

start with, both the parallel and series circuits, and then, with the voltage

set to 5 volts, measure the current in each circuit with different amounts of

resistors. Having taken each result, I will turn off the power supply, so that

the resistors do not get too hot, because this would change their resistance. I will take measurements of the current at 5 volts, with 1

to 4 resistors in parallel and in series.To ensure that my results are accurate, I will repeat each

reading, and use the average result. For safety, I will make sure that I do not touch any of the

resistors, because they may be hot enough to burn.Apparatus:Voltmeter Ammeter 4 Identical Resistors Power Supply Insulated WiresDiagram: Predictions: I am expecting that with the circuit with resistors in

series, as I add a resistor of a certain resistance, then the overall

resistance will increase by that amount. This is because resistors in series

add together, because the current must go through one resistor, then the other,

losing more power each time. Therefore I predict that as the number of

resistors doubles, then the total resistance will double. With the circuit with resistors in parallel, I am expecting

that as I double the amount of resistors, then the total resistance will halve,

because the current has more material to go through.This concept is similar to that in the experiment in which

you look at how the thickness and the length of a wire affects the resistance.

Using a long wire is like having resistors in series because the current has to

flow through more material with resistance in it, so there is more total

resistance. Using a thick wire is like using several resistors in parallel

because the current has a wider ?route? to flow through, so it should be able to

flow through with more ease, so the total resistance will be less. Results: Resistors in parallel: Number of Resistors Voltage (V) Current (A) Total Resistance (Ω) Average Resistance (Ω) 1 5.01 0.48 10.44 1 5.00 0.48 10.42 10.43 2 5.01 0.96 10.44 2 5.03 0.97 10.42 5.21 3 5.02 1.42 5.22 3 5.01 1.41 5.19 3.55 4 5.01 1.86 3.54 4 5.02 1.86 3.55 2.70 Resistors in Series: Number of Resistors Voltage (V) Current (A) Total Resistance (Ω) Average Resistance (Ω) 1 5.01 0.48 10.44 1 5.00 0.48 10.42 10.43 2 5.04 0.23 21.91 2 5.02 0.23 21.83 21.87 3 5.04 0.15 33.60 3 4.98 0.15 33.20 33.40 4 4.98 0.10 49.80 4 5.03 0.11 45.73 47.77 The possible error in these readings and measurements is

0.05 volts and 0.05 amps.Analysis: Looking at the graph, you can see that with a circuit with

resistors in parallel, the more resistors there are, the less the total

resistance is, and with the circuit with resistors in series, the more

resistors there are, the higher the total resistance. This ties in with my prediction that more resistors in

series means a higher resistance, and more resistors in parallel means a lower

resistance.The graph for resistance against number of resistors in

parallel shows us that the resistance is inversely proportional to the number

of resistors in parallel. Ohm?s Law tells us that R=V/I which means that

resistance is inversely proportional to the current, so this means that the

amount of resistors in parallel is proportional to the amount of current that

is getting through.The graph for resistance against the number of resistors in

series, is directly proportional, which means that if you were to double the

amount of resistors in series, then the total resistance would double, which

proves the idea that current going through consecutive resistors loses power in

one, and then loses the same amount of power in the next resistor. This power,

or energy, is being converted into heat energy in the resistor.I think that the result from the circuit with four resistors

in parallel is an anomalous result, because the other three are all in a

straight line, directly proportional to the resistance. Instead of using the

average, it would be more sensible to use the result of 45.73Ω with four

resistors in series, and disregard the result of 49.80Ω.


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