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).
Problem
What type of bulb and wattage produces the most heat?
Grade
Subject
Science
Materials
- A goose-neck style lamp (make sure it can safely use all light bulbs listed!)
- 6 Incandescent light bulbs: 25 watt, 40 watt, 60 watt, 75 watt, 100 watt, and 150 watt
- 2 Compact Fluorescent light bulbs: 7 watt, 23 watt
- Thermometer
- Measuring tape or yard stick to measure distance between the thermometer and light bulb
- White towel
- Stopwatch
- A piece of paper and pencil to record your observations
Procedure
- Lay out the white towel on a flat table.
- Place the lamp on one end of the towel.
- Making sure the lamp is unplugged, screw in lowest wattage bulb and keep the lamp turned off.
- Place the thermometer at the other end of the towel.
- Measure the distance between thermometer and light bulb.
- Check and record starting temperature of thermometer.
- Making sure the lamp is pointed at the thermometer, turn the lamp on and start the stopwatch.
- After 5 minutes have passed, measure and record the temperature on thermometer.
- Turn the lamp completely off and wait for the light bulb to cool down before removing it.
- Make sure that the thermometer has also cooled down to the initial starting temperature you recorded.
- Repeat steps 2-9 with the next highest wattage bulb until you’ve tested all the bulbs.
**Things to Remember**
- Always wait for the bulb and thermometer to cool down before testing any new bulbs!
- Be sure the lamp is turned off and unplugged completely when switching bulbs.
- Make sure distance between bulb and thermometer is the same for each trial.
- The starting temperature should always be the same for each trial.
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.
Why?
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).
Conclusion
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.
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As a seasoned enthusiast and expert in the field of physics and energy conservation, I'm well-versed in the principles that govern the transformation of energy from one form to another. In this context, the science project titled "Let there be light!" explores the fascinating interplay of electrical energy, light, and thermal (heat) energy within the framework of the conservation of energy.
The project investigates the heat production of different types of light bulbs, specifically incandescent and compact fluorescent lamp bulbs (CFLs), across various wattages. The setup involves a goose-neck style lamp, six incandescent bulbs ranging from 25 to 150 watts, two CFLs of 7 and 23 watts, a thermometer, measuring tape, a white towel, a stopwatch, and a recording tool.
The experimental procedure is meticulously outlined, emphasizing the importance of consistency in factors such as distance between the bulb and thermometer, waiting for the bulb and thermometer to cool down, and ensuring the lamp is turned off and unplugged during bulb changes.
The observations and results of the project reveal a direct correlation between the wattage of the bulbs and the temperature they generate. Higher wattage bulbs, such as the 150-watt incandescent bulb, produce more heat compared to lower wattage bulbs and CFLs. The explanation lies in the fundamental differences between incandescent and CFL bulbs.
Incandescent bulbs generate light by heating a metallic coil (filament) surrounded by gases to a high temperature, releasing 90% of their energy as heat. In contrast, CFLs create light through the interaction of invisible UV light with the bulb's coating, making them more efficient and longer-lasting.
The conclusion drawn from the project is clear: incandescent light bulbs generate more heat than compact fluorescent bulbs due to their reliance on metals, gas, and heat, as opposed to CFLs, which leverage a reaction between internal and external materials.
This experiment not only provides hands-on experience with the principles of energy transformation but also sheds light on the practical implications of choosing different types and wattages of light bulbs in terms of energy efficiency and heat generation.
For those interested in delving deeper into related concepts, exploring projects on heat conduction, color and heat absorption, and the angle of light radiation could offer additional insights. Understanding the science behind light and heat has wide-ranging applications, from energy-efficient lighting choices to broader considerations of heat in various scientific contexts.
