You'll cook an egg white just long enough for some parts of the egg to solidify, while the rest remains partially cooked. In the experiment described below, you'll remove the rotating platter (if your oven has one) in order to see the effects of the interference pattern on your cooking. This is why many microwave ovens have rotating platters to promote more even cooking of the food. The interference patterns can create "hot" and "cold" spots in the oven-areas where the microwave energy is higher or lower than average. In a microwave oven, interference occurs between waves that are reflected from the inside surfaces of the oven. Interference is the name physicists use for this kind of combination of waves. When a wave crest and a wave trough coincide, they tend to cancel each other out. When two wave troughs coincide, they combine to make an even lower trough. When two wave crests coincide, they combine to make an even higher crest. For example, at the beach, the incoming waves from the ocean and the outgoing waves from the surf drawing back from the beach interfere with one another. Interference is what happens when multiple waves interact. These properties are interference and the relationship between a wave's speed, its frequency, and its wavelength. In this project you will take advantage of some physical properties of waves in order to estimate the speed of light. (Illustration from Abrisa Glass & Coatings, 2005) X-rays, light, and microwaves are all examples of electromagnetic waves. Light (the part of the electromagnetic spectrum that we can detect with our eyes) is only a small portion of this range. Electromagnetic radiation covers a huge range of wavelengths. Wavelengths between 400 and 700 nanometer are visible as colors and make up a very small portion of the electromagnetic spectrum.įigure 1. The focus of this diagram is to display the portion of the spectrum that is visible to the human eye. The electromagnetic spectrum extends from very short wavelength gamma rays to very long wavelength radio waves. As you can see in Figure 1 below, the range of microwave wavelengths is from 0.01 cm to 10 cm. The absorbed microwave energy heats these molecules and cooks the food. Microwaves work well for cooking because their energy can be efficiently absorbed by molecules commonly found in food, including water, sugars, and fats. So waves with high frequency have short wavelengths, and waves with low frequency have long wavelengths.Įlectromagnetic waves interact with materials in different ways, depending on the nature of the material and the frequency of the electromagnetic wave. The wavelength of an electromagnetic wave is inversely proportional to its frequency. As the frequency decreases, so does the energy. Electromagnetic waves cover a huge range of frequencies, from high-frequency gamma rays and x-rays, to ultraviolet light, visible light, and infrared light, and on into microwaves and radio waves. They do not depend on an external medium-unlike a mechanical wave such as a sound wave which must travel through air, water, or some solid medium. Electromagnetic waves can travel through the vacuum of interstellar space. Microwaves, like light, are an example of electromagnetic waves.
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