Faraday cage

[Scylax]

Does sitting in a car during an electrical storm provide protection by
acting as a Faraday Cage ?

[Stephen_G]

Sort of. Have a look at this from Top Gear...

[excelsior-1]

i'm pretty sure that cars are designed accordingly

[THECORBYLOON]

I mind on seeing a programme a few year ago about a similar test but they weren't allowed to do it here. They had to go abroad and a stuntman drove a car around and it was struck each time, the only effect it had was that the rear wiper made a sweep.

[rojash]

Good to know they can generate 2,000,000 volts of PURE electricity - I mean, you wouldn't want your electricity to be full of nasty E numbers, would you?

[Scylax]

I am obliged, folks. The only question remaining is...how does a radio signal eg,
a mobile telephone signal enter, or leave, a Faraday Cage ?

[ChuckFickens]

A car is only a partial faraday cage there are flaming great big gaps in it called windows.

[New Judge]

The main protection provided against lightning strikes in a car is provided by its rubber tyres. Lightning seeks to find the easiest route to earth and an inch of solid rubber at each corner of the vehicle affords considerable protection.

A better example of a Faraday Cage is an airliner. Aircraft are often struck by lightning but usually suffer no damage.

[ChuckFickens]

"and an inch of solid rubber at each corner of the vehicle affords considerable protection."

So this bolt of lighting that has traveled a few miles through air to get to the ground suddenly can't make the 20CM jump to ground from the car body.... it's nothing to do with the tyres insulating the car, it's because the metal body of the car transfers the lighting around the occupants....millions of volts at 10's of thousands of amps is not going to care one little bit about a few inches of rubber or a couple more feet of air.

[bookbinder]

A radio signal can enter or leave a car/Faraday cage because the aerial is on the outside of the car. Yes?

[ChuckFickens]

Not for a mobile phone they're not, the signals get through the windows.

Some cars are fitted with athermic windscreens (or thermal windscreens) that have a thin metallised coating on them to block heat from the sun (a lot of large buildings have similar windows for the same reason) and it's a commonly known fact that sat navs don't work in cars with such windscreens because the metal coating on the windscreen blocks the signal from the satellite

[Thatcherite]

radio signals for phones are just light at a different wave length and as such penetrate most things that's why they work in your house too. As far as static electricty goes a car will act as a faraday cage. The tyres have no insulation effect at all as the level of energy means that it just jumps through the air. In the Top gear test they do show the arc leaving the bottom of the car. Just don't touch anything metal inside the car!

[Scylax]

My word...my blood-physics level has risen by 10%. Thank you, Chuck, Thatcherite et al. Logical that a high voltage, high amperage arc will easily
bypass the tyres and find earth only cms. from the metal wheels.
It occurs to me also that one could find an illegal use for metal-lined containers
to thwart security measures in shops, libraries, etc. I won't try it....promise.

[drmike]

Hi, Yes it does. The car sub-frame is a Faraday cage; the car tyres are rubber so perfect insulators between Earth. There was a TV program that proved it by driver around an electric sub-station with arcs of electric zapping it at regular intervals. The driver was fine.

Mike

[drmike]

I'm back. I was curious so looked it up and found this: http://www.mos.org/sln/toe/cage.html. I was wrong all round it seems, other than it being safe!

Mike

[pdq1]

///A better example of a Faraday Cage is an airliner. Aircraft are often struck by lightning but usually suffer no damage.///

New Judge the problem with modern airliners is that they do not possess a metal fuselage but are made from composites including plastic. The new Dreamliner by Boeing is a case in question. I believe they get round this by having wire harnesses within the fuselage but is this completely safe? Only time will tell after they have done a few air miles.

[nungate]

I flew on a 737 which flew through and landed in an electrical storm there were no problems to the best of my knowledge

[pdq1]

Nungate Can I recommend the item by Lazygun 2 questions down on 'Chance'. Makes an interesting watch.