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Heat from Light Bulbs
Let there be light! At the flick of a switch, a light bulb can light or illuminate an entire room, but what else is happening? One the basic laws of physics, the conservation of energy, tells us that energy is neither created nor destroyed: rather, it can only be transformed from one form to another. In the case of the light bulb, electrical energy is being transformed into light and thermal (heat) energy. Different wattages and types of bulbs give off varying amounts of light and heat. In this light bulb science project, we'll be working with incandescent and compact fluorescent lamp bulbs (CFL’s).
What type of bulb and wattage produces the most heat?
Observations & Results
What did you observe? You may have noticed that the higher the wattage, the highter the temperature. The 150-watt incandescent bulb should have yielded your warmest measurement (Why do you think this is?), while the CFL’s should have been much cooler than most of the incandescent bulbs.
So what’s the difference between incandescent bulbs and compact fluorescent bulbs? An incandescent bulb emits light through the heating of a small metallic coil called a filament surrounded by gases that heat to approximately 4000 F! While providing plenty of light, they release 90% of their energy as heat making them fairly inefficient in comparison to compact fluorescent lamp bulbs.
Compact fluorescent bulbs create invisible UV light that interacts with the coating of the bulb in order to create visible light. They are known to be more efficient and longer-lasting (and as you may have noticed, take longer to heat up).
Incandescent light bulbs burn much hotter than compact fluorescent light bulbs do. They possess very different properties—incandescent bulbs rely upon metals, gas and heat, while CFL’s rely more upon a reaction between the internal and outside materials. For these reasons, incandescent lights emit more heat energy than CFL’s.
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.