The Relationship Between Resistance, Potential Difference and Current in an Electric Circuit

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Experiment 1
Aim:
To test the influence that the potential difference will have on the current of an electric circuit.
Investigative Question:
What would the effect of the change in potential difference have on the current of the circuit, if the temperature in the circuit remains constant?
Hypothesis:
By decreasing the resistance in the electric circuit we will be increasing the total potential difference in the circuit and will therefore directly strengthen the current in the circuit. The relationship between potential difference and current strength will be directly proportional.
Variables:
Independent Variable:
Potential difference (V) in the circuit.
Dependent Variable:
The current strength (mA) in the circuit.
Controlled Variable:
The temperature in the circuit is kept constant throughout all tests.
Apparatus:
A circuit board.
6 Crocodile wires.
A light bulb.
An ammeter.
A voltmeter.
A rheostat resistor.
Three 1,5V cells forming a 4.5V battery.

Diagram:

Method:

Safety precautions:
Ensure that the circuit is away from any water.
Ensure that all apparatus being used is in working condition and has its certificate of safety.
Ensure that all wires are insulated as to avoid any short circuitry or electrical burns.
Ensure that all batteries being used are not leaking or damaged (check shelf life of batteries).

Accuracy Precautions:
Ensure batteries are fully charged to ensure accuracy of readings.
Ensure that the ammeter and voltmeter are calibrated accordingly.
Ensure that the rheostat is fully operational.
Ensure that the light bulb is fully operational and the filament is still attached blown before commencing with the experiments.

Experimental Procedure:
Set up experiment as seen in the diagram ab...

... middle of paper ...

...ining potential difference can be solved by subtracting the potential difference (voltage across the circuit) from the EMF (electromotive force) therefore allowing us to calculate the amount of total resistance within the electric circuit.
Conclusion:
We can therefore conclude that the internal resistance of the battery in this electric circuit is non-negligible and can influence the readings taken off the circuit, hence proving the hypothesis of this experiment to be correct.

Discussion:
Now as this experiment depends completely on the factors that affect the cells in use, each different test would provide new results but would still show the internal resistance of the battery.
Bibliography:
Mann, M. May 2012, Mind Action Series Physical Sciences 11, Allcopy Publishers, Sanlamhof.
McLaren, C. December 2012, Physical Sciences 11, MacMillan Publishers, Cape Town.

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