- #1
menniandscience
- 99
- 2
why we can heat food with microwave and not light wave (the light we can see) fast?
Lightwave Oven: Why We Heat Food With Microwave
In summary, microwaves are able to heat food because they are attuned to the resonance frequency of water molecules, causing them to oscillate rapidly and generate heat. This is known as dielectric heating and is more effective than light waves, which can only heat the surface of food. The frequency of 2.45 GHz was chosen for microwave ovens because it was not in use for communications or radio astronomy.
- #2
Danger
Gold Member
- 9,799
- 253
I'm not sure that I'm using the proper terminology here, but essentially microwaves are attuned to the resonance frequency of water molecules, and so make them oscillate rapidly. That's what causes the heat. It's more complicated than that, but someone else can help clear it up for you.
- #3
negitron
Science Advisor
- 848
- 2
Not quite. Liquid water doesn't have a well-defined resonance and microwave ovens at 2.45 GHz operate well below the peak resonance of water vapor at around 30 GHz. Instead, microwaves heat by a process called dielectric heating, in which polar molecules (in foods, mainly water but also fats and sugars) are tugged back and forth extremely rapidly causing them to bump and slam into neighboring molecules, imparting kinetic energy--heat. Light can heat too--you never burned ants with a magnifying lens as a kid? The problem with light is it doesn't penetrate very far before being entirely absorbed so only the surface gets heated; microwaves can penetrate more deeply, allowing for more thorough cooking. Why 2.45 GHz? At the time these ovens were being invented, nothing really used this band: communications used much lower frequencies and radio astronomy used higher ones so a frequency was chosen that was relatively unused. There's nothing special about it in terms of heating capability. Industrial microwaves used for things like curing glues typically use 915 MHz.
- #4
menniandscience
- 99
- 2
thanks
- #5
Danger
Gold Member
- 9,799
- 253
Thanks, Negitron. I knew that I didn't have it quite right, but wasn't sure why. 
1. How does a lightwave oven work?
A lightwave oven uses electromagnetic waves, specifically microwaves, to heat food. These microwaves are directed into the oven's cooking cavity and are absorbed by the food, causing the water molecules in the food to vibrate and generate heat. This heat then cooks the food from the inside out.
2. Is it safe to use a lightwave oven?
Yes, lightwave ovens are generally considered safe to use. However, it is important to follow the manufacturer's instructions and avoid using materials that are not microwave-safe. Also, it is important to keep the oven clean and free of any food debris to prevent potential fire hazards.
3. Are there any foods that should not be cooked in a lightwave oven?
Yes, there are some foods that should not be cooked in a lightwave oven. These include eggs in their shells, whole fruits and vegetables, and foods with a high water content such as hot dogs or grapes. These foods can potentially explode or burst due to the rapid heating process in a lightwave oven.
4. How does a lightwave oven differ from a conventional oven?
A lightwave oven uses microwaves to directly heat the food, while a conventional oven uses convection to circulate hot air around the food. This means that a lightwave oven can cook food much faster than a conventional oven, but may not be able to achieve the same browning or crispy texture that a conventional oven can.
5. Can a lightwave oven have any negative effects on the nutritional value of food?
No, there is no evidence that using a lightwave oven can have any negative effects on the nutritional value of food. In fact, because food is cooked quickly and evenly, it can potentially retain more nutrients compared to other cooking methods. However, overcooking food in any type of oven can lead to a loss of nutrients.
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