Ask Fuzzy: Are microwave ovens dangerous? Is it safer to turn them off when they're not in use?

Nuclear waste from these sources include materials such as radioactive iodine and caesium, which are not things you'll find in a microwave oven. They do not involve nuclear reactions or any of the waste products you'd get from an H-bomb.

Also generated in nuclear reactions are emissions in the electromagnetic spectrum. That sounds less daunting when you think that bedside lamps and rainbows produce these as visible light. They are part of the spectrum with radio and microwaves at one end, and X-rays and gamma rays at the other.

X-rays and gamma rays can be dangerous in higher doses because they can alter the materials they hit. Microwaves are far less energetic, and their most likely effect is that they can induce some heating.

Microwave ovens heat by exciting water and fat molecules.

This effect was first noticed in 1945 by an engineer who stood near a piece of radar equipment, and found the chocolate bar in his pocket starting to melt.

This effect became well known among sailors who'd sometimes deliberately stand near radar transmitters during cold sessions on watch.

Not long after that, engineers began using microwaves to heat popcorn.

It's sometimes said that microwave ovens heat food from the inside-out, but this isn't correct.

It can appear that way when the contents are inside dry packaging which doesn't get hot, while the moist food inside does. This just means the packaging is not absorbing microwaves.

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An oven will not emit any microwaves unless the door seals are damaged. If that does happen it's possible to get burnt.

One person described what happened when the door switch on their oven was defective: "I felt as if really warm water had been run over my stomach area where I had the door opened."

Without power, an oven can't generate any microwaves - it's nothing more than an inert assembly of wires and metal.

Still, you might want to turn yours off at the wall- not for safety reasons, but because, even when not in use, they trickle away "vampire power".

So many devices around the home continue to draw electricity even when supposedly idle, typically consuming 10 per cent of household power bills.

Listen to the Fuzzy Logic Science Show at 11am every Sunday on 2XX 98.3FM.

Send your questions to AskFuzzy@Zoho.com Twitter@FuzzyLogicSci

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