Lesson Three : Activities and Quizzes
Activity 2: The Color of HeatRequired materials: A lamp with a 100 Watt filament light bulb, a stovetop range, a box of matches, and a propane torch.
NOTE: All of the objects in this activity are very hot. This activity should only performed with strict adult supervision.
Procedure: This activity requires the students to determine which objects are hottest by observing the color of the light emitted. Remember, the hotter the object, the shorter the wavelength of light emitted. The list below is ordered from hottest source to coolest source. The order should be varied during demonstration.
Propane torch: The flame from the end of the torch emits blue light, which has a wavelength of 492 - 455 × 10-9 meter. This flame is the hottest object.
100W Light bulb: When the lamp is switched on, current flows through the tiny filament within the bulb and it heats up to around 2800 degrees Celcius. This high temperature causes the bulb to glow white, which is caused by the wavelength of the emitted light being emitted near the center of the visible spectrum.
Match: When the match is lit, the flame will be yellow, with a wavelength of 597 - 577 × 10-9 meter. This indicates that the flame is slightly cooler than the light bulb filament.
Range: When one of the elements is heated to its maximum temperature, it will glow red, with a wavelength of 780 - 622 × 10-9. This heating element is the coolest object of the four listed here, but it should be made clear that this heating element is still very hot and should not be touched!