# Physics of a Light Bulb

**Topics:**Incandescent light bulb, Percent difference, Ohm's law

**Pages:**3 (891 words)

**Published:**November 13, 2012

Catherine Bellet

Lab Partners:

Natalie Russell

Alex Harris

TA: Chad Lunceford

PHY 114

TH @ 2:25pm

Abstract:

Ohm’s law states, via the equation V=I*R, that the voltage found across a piece of material is proportional to the current. If the temperature remains constant therefore the resistance is found to remain constant. Stefan-Boltzmann law states that when the temperature if above an average of 1000K, then the relationship of voltage and current should be found to be consistent with the formula AT4. The experimental data found in this, Physics of a Light Bulb, experiment both correlates and verifies the Stefan-Boltzmann law. The voltage and current were found to be proportional to one another, verifying Ohm’s law. In addition, the fact that radiation away from the light bulb is indeed proportional to the fourth power of temperature was observed and again verified through a linear fit graph. The percent error found between the two experimental B values was found to be an average 6%. This showing proving that the experiment was decently accurate.

Objective:

To measure the relation between voltage and current in a small flashlight bulb; to determine the temperature of the filament; to verify the Stefan-Boltzmann law of radiation. Procedure:

Begin the experiment by correctly setting up the circuit. Using the DMM set, find the resistance of the cold filament of the bulb at room temperature. Open a pre-set experiment file, than connect the circuit to the bulb. Slowly increase the output signal from the power supply, as the voltage reaches 10V, immediately bring the power supply back down to zero. There should be an observed recorded data and graph in the experimental file. From the recording, highlight the resistance of the cold filament from the data which corresponds to the current ≤0.08A. Apply a linear fit which in return will give the slope, which represents the bulb resistance. Copy and paste the recorded data into...

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