What one is more energetic microwaves radio waves or visible waves?

Answer 1

Visible light has a shorter wavelength, and therefore a higher energy content than microwaves.

You may wonder how this is possible, when microwaves heat up your food so effectively, and

visible light doesn't. That's because a microwave oven produces microwaves that are tuned to

the exact resonant frequency of the water molecule. Otherwise, the microwaves would heat

your food even less than an ordinary light bulb would.

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Your answer is only partially correct. The difference in frequency (visible light is much higher) makes the energy content of visible light 30,000 to 50,000 times greater than that of microwave radiation. Where you are incorrect is saying that the microwaves have "the exact same resonant frequency of the water molecule". Actually, the resonant frequency of water at room temperature is about 22 gigahertz (GHz), while the frequency of the waves in a microwave oven is 2.45 GHz, almost an order of magnitude lower. Further, as the water gets hotter, its resonant frequency increases and so couple the microwave energy less and less; so warm and hot water heat more slowly that cold water.

The major reason visible light isn't used to cook food is that its penetration depth into the food (directly related to its wavelength) is so small that it can only heat the surface - it has virtually no penetration into the food. Visible light has been used, in the form of a halogen bulb in some microwave ovens so the microwave heat or cook the bulk of meat, while the visible light browns and even crisps the surface.