Jared Wainwright asked:
Hello Dr Chris,
Do you get less exposure from the microwaves emitted by a mobile
phone if you use a wired handsfree? I read or heard somewhere that
the aerial for phones has to be a certain size; a lot shorter than the
length of copper in a wired handsfree, meaning it won't act as an
The show is excellent!
Jared (Stoke On Trent)
Dave - It depends on the hands free system. The problem that can happen, as someone discovered in a study a couple of years back, was that some of them were actually receiving the transmission which the mobile phone was making and funnelling them up the wires into your ears.
Chris - Because the microwaves are making electrical current flow up and down the wires?
Dave - Yes, that is exactly right. Essentially you have a funnel into your ear which could actually cause similar, or if not higher, doses around your ears than you would get otherwise.
Chris - How does is turn from electric current back into a microwave in your ear then?
Dave - Any rapidly changing electrical current will produce electromagnetic radiation and therefore, it will be transmitting microwaves all the way up. It should be electronically quite easy to stop that. You just put in a filter which blocks the high frequency radiation, but not all headphones apparently had them. So, it depends is the answer.
Chris - He goes on to say, “Is a microwave oven which is shielded - it has all this protection to stop the microwaves coming out - therefore, less dangerous than a mobile phone?”
Dave - That entirely depends on whether you're in the oven or not. If you're actually in the oven... The biggest problem you get from microwaves is heating. The reason why a microwave oven could cause you damage, and how it cooks meat, is that it produces a huge amount of heat in there. The amounts of heat which should be outside the microwave oven, or that coming from a mobile phone aren’t large enough to significantly change the temperature of your body.
Chris - A microwave is running at say, a kilowatt whereas your phone is running at milliwatts, so the heating effect of your phone on the tissue that it’s irradiating, ie your brain, is going to be tiny in comparison.