Light Bulb Lamp
2009
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In what form was the light energy coming from the lamp before the light bulb changed it to light?
Most likely somwhere near you a light is on. Recall that energy cannot be creatd or destroyed, but only changed from one form to another. In what form was the light energy coming from the lamp before the light bulb changed it to light? Where did it come from? Trace the steps in the transformation of this energy as far back as you can. What happens to the light energy after it shines on you?
If we are talking about a typical light bulb (not compact fluorescent) the filament in the bulb produces light because of the electrical resistance of the filament. The electrical resistance causes the filament to heat up to a very high temperature at which point the filament produces black-body radiation which results in the white light that you see.
As you said, energy is neither created nor destroyed. Therefore, the light energy came from the electrical energy supplied to your house. So where does electrical energy come from? There are a number of different electrical power generating methods, but to simply the problem, let's say that your power comes from a coal power station. The electrical energy from a coal power plant comes from the release of the chemical energy stored in coal. The chemical energy in coal originally came from plants that absorbed energy from the sun and turned into coal over thousands of years. The sun's energy comes from nuclear fusion reactions. Therefore, you can say that the energy supplied by your light bulb really came from energy released by the sun thousands of years ago.
Once the light from the lightbulb is released, it radiates onto the surroundings. The surroundings eventually absorb the light which results in a small increase in temperature of the surroundings. Additionally, near the light bulb, a lot of energy from electricity is released as heat instead of light - that's why regular light bulbs aren't very efficient - they create a lot of heat and not much light.
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