Investigating The Resistance Of A Light Bulb As The Voltage Is Increased.

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Investigating The Resistance Of A Light Bulb As The Voltage Is Increased.

Resistance is the resist of electrons flowing through an electrical component. The resistance slows down flow meaning that the components will heat up due to friction. The current in a circuit gets smaller the bigger the resistance is. To work out resistance you can use this formula Resistance = Volts/Current, R=V/I

To measure the resistance in a circuit you would need to find out what the voltage and the current is in the circuit. To find the voltage of an light bulb in a series circuit and hence the voltage of the circuit you would need to use a voltmeter which would be connect parallel with the light bulb to find the voltage across the bulb (see diagram below). Then you would need to find the current in the series circuit by placing an ammeter in the circuit which would give you the current of the circuit as well as the bulb current (see diagram below) Now you would then divide the volts by the amperes to find the resistance.  

Voltmeter and Ammeter in a circuit diagram

For this experiment I would use a series circuit rather than a parallel circuit due to you only need to test the resistance of a light bulb once rather testing three or four light bulbs in a parallel circuit.

To make the test safe I would make sure that I would work away from water, make sure my hands were dry and not sweaty as water is a conductor which could cause shorting and electric shocks. I would also check if any wires were frayed because if I touched one again I could get an electric shock. I would also check if the cable to the plug connecter was properly connected to the plug grip as loose wires in the actual plug could cause shorting and possibly a fire.  It is also important that all the connections in the actual circuit are properly made for the same reasons.  

How I will set up the experiment and perform the experiment is by getting a power pack plugging it into a socket then I would connect the negative wire in to the power supply, so that no current flows while I am connecting the circuit, and then I would carry on that way plugging the voltmeter parallel to the bulb after that I would plug in the ammeter in the circuit then plugging the wire from the ammeter into the power pack. I would check that the ammeter and voltmeter were connected the right way round to avoid a negative reading.  I would then turn on the power at the mains and then on the power pack. To increase the voltage I would turn off the power on the power pack and then turn a knob to increase the voltage on the power pack. After that I would turn on the power on the power pack to see what effect the voltage had made.

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For this experiment I will need to have the following:

1. Power pack which will be able to increase the load

Of power.

2. An ammeter to measure the current

3. A voltmeter to measure the voltage.

4. A bulb

5. Several wires to connect up the circuit.

Shown on below is the equipment set up in a diagram.

Ohms law states that: the current flowing through a conductor is proportional to the potential difference across it providing the temperature is constant. So therefore if ohms ...

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