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An Investigation To Show How the Voltage Affects the Current In a Light bulb.

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Aim:~ An investigation to show how the voltage affects the current flowing through a light bulb.

Hypothesis:~ I predict that as the current increases the voltage of the lamp will also increase; thus causing the resitance to decrease. I think this because of Ohm’s Law which states that current will increase in proportion to voltage; if the current is doubled the voltage is also doubled.

Bearing this in mind my graph should resemble my diagram below:











If the voltage across a light bulb is increased, more current will flow through it. If the number of bulbs in a series circuit is increased, less current will flow through them. The lamps resist the current, so if you put more lamps into the circuit there is more resistance. As the resistance of the variable resistor decreases the current in the circuit increases until the bulbs burn out.

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image15.png        Variable Resistor

image15.png        12 volt lamp

image15.png        Battery pack

image15.png        Wires

image15.png        Crocodile clips











Planned Method:~ I will set up the apparatus

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To make this experiment more accurate I could have used electronic equipment which would accurately measure the volts and amps so that there would be no human errors. To extend this investigation I could have used different types of bulbs with a different size of maximum voltage. I could have taken more readings, perhaps repeated the experiment a few more times and used a wider range of current.

I will do a preliminary test to find the range of current in amps. I will do this by moving the variable resistor to its lowest and highest points and noting down the amps. In this case the lowest point is 0.5 and the highest is 1.6 amps.

I will start with 0.5 amps, working systematically, I will note down the voltage every 0.1 amps. I will do this until I reach the highest point which is 1. 6 amps. I will then repeat this to see if my results have changed or are the same.

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