Investigation into the resistance of a filament lamp

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Investigation into the resistance of a filament lamp

Aim: To investigate into the resistance of a filament lamp.

Background Information

Filament Bulb

The tungsten light bulb is supported by several molybdenum wires. The ends of the support wires are imbedded in a glass button at the top of the glass support rod.

The copper and nickel led-in wires, which carry current to the filament, are supported by a glass support system.

The filament of a light bulb is a resistor of no other. When current passes through the resistor electrical energy is converted into heat. A light bulb converts current into power by the resistive element inside the light bulb.

When the power level is sufficient to raise the temperature above 1000 degrees Kelvin, visible light is produced which can help us to estimate the temperature of the filament.

The current through the light bulb is not proportional to current and doesn’t obey Ohm’s law, because the current through the filament causes it to heat up.

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As the temperature of the filament changes the resistance also changes.

Problem Identified

I have decided to investigate into the resistance of a filament lamp. I will measure the current and potential difference of the filament lamp at various points, after measuring current and potential difference I will draw a graph to show the relationship between current and potential difference.

By finding 1 over gradient of the I/V characteristic graph we can work out the resistance of the filament lamp. When we find the resistance of the filament lamp we can compare resistance of the ...

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