Electricity

[Douglas]

Man in pool would actually stick out as an easy target so to say for lightning. You must also take into account that water has very high resistance and a pool of water might as well offer more resistance than a man.

 

I for one wouldn't stay inside a lake or a pool during a thunderstorm )

I've measured the resistance of tap water, and as I recall, it was about 10 Kohms per inch. Water with a high mineral content and salt water would be less.

[5614]

doesnt air have a higher resistance than water?

i think it does, in which case, the lightning would go straight to water, rather than dancing around in the air, trying to find ground [not via the water]

 

what acts as a 'ground' for electricity?

 

would you [person] count?

would the bottom of a swimming pool count?

would the bottom of the sea count?

or is it only earth?

___

 

however, i think its pretty safe to say that it is not safe to be in water during a lightning storm... also not that safe to be near water, as the current passes over or through the water, resulting in a current at the edge of the water.

[Lance]

doesnt air have a higher resistance than water?

i think it does' date=' in which case, the lightning would go straight to water, [b']rather than [/b]dancing around in the air, trying to find ground [not via the water]

 

What?! Lakes and pools are at the same level as the surrounding land so that doesn’t make much of a difference. Also, generally during a thunderstorm it’s raining too... which would make the ground even more conductive AND grounded...

 

I think this is a petty argument anyway. It may not be safe to be near water during a thunderstorm but that doesn’t mean it’s any less safe not to be around water.

[5614]

it isnt safe to be around water, as water will atract the lightning, coz water is less resistant than air so the lightning is going to go through the water...

 

now obviously if its pouring with rain, then theres not gonna be much of a difference, but even if it is raining, there is a difference between being in the rain, and being in a swimming pool.

[Lance]

it isnt safe to be around water' date=' as water will atract the lightning, coz water is less resistant than air so the lightning is going to go through the water...

[/quote']

 

It doesn’t matter how resistant the pool is because it’s at a lower height than the surrounding land. Therefore striking the lower pool would ADD resistance.

 

Question: Is lightning attracted to water or other objects on the ground?

A cloud-to-ground flash usually begins in a cloud at 15' date='000 to 20,000 feet above ground. It comes to earth in 50-yard steps. Until it's close to the ground, it has no idea of what it will hit. Then, within 30 to 50 yards of the ground, lightning decides what is the best connection to make with the surface. Often, the best connection is the tallest object within the 30 to 50 yard area.[/quote']

[Douglas]

it isnt safe to be around water, as water will atract the lightning, coz water is less resistant than air so the lightning is going to go through the water...

Keep in mind that the air in the path of the lighting is ionized. Ionized air has a much lower resistance than the air we breath

[Lance]

Keep in mind that the air in the path of the lighting is ionized. Ionized air has a much lower resistance than the air we breath

 

In fact it has very little resistance at all. There was a guy who performed on stage with a tesla coil and he would attract the streamers to his body. One day the streamers contacted a mains outlet and mains electricity flowed through the ionized streamers and into the guy attracting them. Needless to say the guy died.

[5614]

It doesn’t matter how resistant the pool is because it’s at a lower height than the surrounding land. Therefore striking the lower pool would ADD resistance.

yeah, but i was just kinda thinking of a pool at exact ground height, so we dont have the height = resistance thing again!

 

water lower than land will not attract lightning, because it would mean more resistance to add to the journey to reach the pool

will water at the same level as land attract lightning, as it is easier for the lightning to reach it [assuming that the lightning orginated above the pool] but what has more resistance: the air, or the water, [remember that the air would be ionised]

water above ground level will attract lightning, [obvious]

[Douglas]

yeah' date=' but i was just kinda thinking of a pool at exact ground height, so we dont have the height = resistance thing again!

 

water lower than land will not attract lightning, because it would mean more resistance to add to the journey to reach the pool

will water at the same level as land attract lightning, as it is easier for the lightning to reach it [assuming that the lightning orginated above the pool'] but what has more resistance: the air, or the water, [remember that the air would be ionised]

water above ground level will attract lightning, [obvious]

What you're really asking here is.......does ionized air have less resistance than water, since lightning takes the path of least resistance.

Do a google and type in "resistance of ionized air" or something like that.

Then do a google and type in "resistance of distilled water"......I'm saying distilled because it's pretty specific.

[pulkit]

A) Air will only ionise once lightning has passed through it and not before that.

B) Once air breaks down electricity, it will offer next no resistance to flow of charge

C) Distilled water is a very bad conductor, in practical situations water will have a much larger conductance.

[Douglas]

A) Air will only ionise once lightning has passed through it and not before that.

B) Once air breaks down electricity' date=' it will offer next no resistance to flow of charge

C) Distilled water is a very bad conductor, in practical situations water will have a much larger conductance.[/quote']

I disagree, the charge builds up, the air ionizes, then lightning discharges through it.

 

I disagree, the resistance is quite high. If you hook a spark plug to a variable high voltage transformer, you crank up the voltage, the air ionizes, the spark jumps, you lower the voltage to roughly half...maybe less and the spark stops.

 

I used distilled water as an example, since it is specific enough, I could have used salt water (the saltiest that water can get) and used that).............whatever

[5614]

ionisation of the air is caused by the lightning, you say " the charge builds up, the air ionizes, then lightning discharges through it." but nothing actually causes the air to ionise, however in pulkit's and my version of things, the spark ionises the air.

 

pure H2O is a rubbish conductor, normal tap water with maybe some salt as well conducts quite well

[pulkit]

Sparking in a plug occurs only because, beyond a certain voltage the air near the plug suffers from a dielectric breakdown or electric breakdown. Only once this has occured due to a sufficiently high electric field, does the air begin to conduct and hence you see a spark. The spark exsists only because the air is conducting. And the air conducts only because it was broken down due to high electric fields.

 

I may be slightly wrong in point A of my previous post, but not completely. No charge accumulated 20,000 feet up in the air can cause dielectric breakdown of air near the ground, that will happen as the lighning passes down. I think Lance already mentioned that lightning moves in steps of 50 yards or so, that ought to explain what I just claimed.

[Douglas]

Sparking in a plug occurs only because' date=' beyond a certain voltage the air near the plug suffers from a dielectric breakdown or electric breakdown. Only once this has occured due to a sufficiently high electric field, does the air begin to conduct and hence you see a spark. The spark exsists only because the air is conducting. And the air conducts only because it was broken down due to high electric fields.

 

I may be slightly wrong in point A of my previous post, but not completely. No charge accumulated 20,000 feet up in the air can cause dielectric breakdown of air near the ground, that will happen as the lighning passes down. I think Lance already mentioned that lightning moves in steps of 50 yards or so, that ought to explain what I just claimed.[/quote']

The air between the electrode and ground ionizes.

 

Lightning travels at nearly the speed of light.

 

300KV or more, will ionize the air at 20,000 feet

[5614]

300KV or more, will ionize the air at 20,000 feet

why? prove it?

 

surely as the flow of electrons [lightning] passes through the air then the air is ionised, not before?

[canadianpoet]

I don't think a pool or lake would attract the lightning anyway! Once lightning reaches the ground, the air close to the ground becomes ionised, and then 'streamers' flow upwards from all surrounding objects towards the oncoming bolt, and which ever makes a connection first is the overall lighting bolt! This had been scientifically tested, proven and even filmed! I don't think a (relatively) small body of water would send streamers up to the lightning. I'm not saying lakes don't get struck or that you are safe if you’re floating about in one during a storm. But I think the chances of one being struck as opposed to a nearby tree or hill top is very remote.

 

And 300kV will not ionise the entire sky, there's no where near enough juice to do that! The air is only ionised when the bolt is very close to the ground, once the streamers go up. It's the ionisation that sets the streamers off! But obviously, 5614 was correct when they said that the air is ionised once the lightning has passed through it.

[5614]

thank you thank, *takes a bow*

 

just to point out, lightning takes the path of least resistance.... to lightning [basically, although not technically] air has the highest resistance it is likely to meet, therefore on coming down it will gladly transfer to a tree of anything higher than the surrounding ground level... tree, person, mountain - anything.

 

if you had totally flat ground and there was a swimming pool and the lightning struck above the swimming pool, then the lightning would go down, straigth to the water and through the water to the ground, which has less resistance if the lightning went through the air and across in the air into the ground. [instead it goes through the water.

 

however if there was a tree around, because the tree is higher and has less resistance than air, the lightning will 'jump' to the tree, assuming that the extra distance it travels + resistance of tree equal less than the resistance of carrying on directly to the ground.

[Primarygun]

I don't think a pool or lake would attract the lightning anyway!

Really?

[5614]

yes really, read the rest of the thread, if you have a pool of water and a have a tree next to it, the tree will attract the lightning not the water, as the water is the same level as the ground, so the lightning will go straight down, as straight is the shortest route, unless theres a tree, which it will jump to, as that cuts out the higher resistance of air [assuming the tree is near by, not sure of exact distances involved, to work it out, you need to know resistance of air Vs. resistance of tree]

[Primarygun]

Do the electrons move from the sky towards the ground or just the electric shield move?

I know that a closed circuit, the electrons only move a very small step, but the shield move with the speed of light.

Is this determined by the voltage? Is the charge difference also considered(like the sky and the ground)?If so, why doesn't lightning act go to the upper?there is a larger difference of the charge./

[JohnB]

Interesting subject.

 

My take on it is this, a person floating in a pool will not get electrocuted, but a person standing on the bottom will. This is because the first person is not earthed while the second one is.

 

By analogy, you are in a car and a powerline falls and drapes over your vehicle. While you are in the car, you are safe. (At least until the tyres blow.) As you are part of the medium, current doesn't flow through you. Should you attempt to leave the car however, as your foot hits the ground you become earthed, and fry.

 

Consider the guys who work on the high tension power pylons. (I can only assume that the methods are similar around the world.) In Oz, when using a helicopter for working on the lines, the repairer leans out of the chopper and touches the line with a conducting rod. He then hooks himself to the line with a conducting cable. He can then work on the line with complete safety. While he is part of the circuit, as he is not earthed, no current flows through him.

 

Bizarre, I know, but that's what the fellow that does it told me.

[YT2095]

anyone here heard of PD? (Potential Difference)?

 

they`re BOTH gunna get zapped! (dependant on the proximity due to saline resistance).

if you think the guy in the swimming pool is going to be any safer than the guy standing up your mistaken, how else can an electrical appliance in a bath kill you?

 

 

PD... if a lightning bolt has 1,000,000 volts to it, and the water is 10 foot deep, you`ll get 100,000 volts per foot of water cubed, and if you`re 6 foot tall, expect to get a healthy percentage of that power!

 

the only difference is that the guy standing is more likely to get hit, than the guy in the pool.

[Douglas]

anyone here heard of PD? (Potential Difference)?

 

they`re BOTH gunna get zapped! (dependant on the proximity due to saline resistance).

if you think the guy in the swimming pool is going to be any safer than the guy standing up your mistaken' date=' how else can an electrical appliance in a bath kill you?

 

 

PD... if a lightning bolt has 1,000,000 volts to it, and the water is 10 foot deep, you`ll get 100,000 volts per foot of water cubed, and if you`re 6 foot tall, expect to get a healthy percentage of that power!

 

the only difference is that the guy standing is more likely to get hit, than the guy in the pool.[/quote']

It boils down to the path of "least resistance". If the guy on the ground is wearing 1 inch thick rubber soles, then the guy in the pool may be zapped, if the guy is barefoot on the ground then he may get zapped.

As for the "bath and appliance", with today's PVC pipe, fiber glass tubs and plastic faucet's etc, there may not be enough current to kill the person, as opposed to baths with metal tubs, metal faucets, copper tubing water inlets, which go straight to ground.

[YT2095]

WHO CARES! about "todays" modern way, it`s utterly irrelevent to the point, in the OLD DAYS it would kill you!

the principal is still valid whether or not it applies now or then, a WW2 V2 rocket killed 1000`s in the war, it won`t happen now, does that mean V2`s can`t or havent Killed?

[Douglas]

WHO CARES! about "todays" modern way' date=' it`s utterly irrelevent to the point, in the OLD DAYS it would kill you!

the principal is still valid whether or not it applies now or then, a WW2 V2 rocket killed 1000`s in the war, it won`t happen now, does that mean V2`s can`t or havent Killed?[/quote']

It's absolutely relevant, if there are two people, one standing in a tub made from fiberglass and PCV piping and the other person standing in a tub made of metal with copper tubing, this forms a parallel circuit, with the person in the metal tub having much less resistance to ground, 100 milliamps may flow through him, where 10 microamps may flow through the other person. One dies, the other doesn't.