Simple electricity theory

[Link321]

Hello,
Im currently at college studying science and we have recently started our electricity module, unfortunately our tutor has been Ill so we've just been given worksheets and they have raised a few questions about the principals of electricity. Basically one of the questions I have is relating to the chance of getting an electric shock; would I be correct in thinking that if a person is not in contact with earth they cannot get an electric shock? So if they jumped and grabbed two live wires they wouldn't feel a thing and would be fine? (I know it's unlikely but....) any more info along this lines would be great.

(P.s, apologies if I've posted this in the wrong place)

 

[Sintra]

This is a worrying question. The 2 live wires you touch could be at very different potentials.

 

[Darkwood]

I would as a class approach your college and express your concerns that due to your teachers ill health you are not getting the education you and all your class are paying for... as this is the first full week gone 2014 and we just had xmas etc just how long has your tutor been ill?

You need to be in contact at two points if their is a potential difference between them and the voltage is high enough then the current will flow through your body whether it was between 2 wires at differing potential or a wire and earth.... if you could hover and only touched live you would not get a shock as you dont make a circuit...

There're plenty of easy to follow pictorial stick man diagrams that demonstrate this and this should be within your course work and notes.

 

[Link321]

Thanks for the help,
We have approached our college, and the response is the usual 'We're working on it'
To be fair the biology parts of the course were good, It's just our physics teacher has been off and not covered well for 2 months or so. I get most of it, It's just I couldn't get to grips with this bit.
So basically If you were to hover and touch too live cables of 230v you wouldn't get a shock, But if you touched a 230v and 400v cable you'd get a belt?

 

[yellowvanman]

if you could hover and only touched live you would not get a shock as you dont make a circuit...

real life example - birds sitting on an overhead live cable

 

[7029 dave]

would not like to put it to the test. lol

 

[Darkwood]

Thanks for the help,
We have approached our college, and the response is the usual 'We're working on it'
To be fair the biology parts of the course were good, It's just our physics teacher has been off and not covered well for 2 months or so. I get most of it, It's just I couldn't get to grips with this bit.
So basically If you were to hover and touch too live cables of 230v you wouldn't get a shock, But if you touched a 230v and 400v cable you'd get a belt?

NO!...not exactly when you say a wire is 230 or 400v you have to say relative to what! Earth? Each other? etc... saying one is 230 and one is 400 means nothing without a reference to another point.

When you measure a voltage it is between 2 points this could be Live to Neutral or Earth or in multi-phase systems Live to Live.

2 wires can have a potential each of 230v to earth but if they were on different phases the voltage between the two wires could be 400v
If each wire was on the same phase both could still have 230v to earth but will show 0-volts between them as they are the same phase so no potential difference.

You have to know the potential difference of the 2 points you are in contact with if a PD of high enough voltage exist and you touch the 2 points then current will flow through your body.

If you don't create a circuit then you will not get a shock so if you could float up to a pylon and sat on a cable at 400 000v olts and you were totally clear by a good distance of all other wires and earth then you would not receive a shock although getting you down would be interesting :hanged:

 

[ifindoubtdont]

Have a search for "Faraday Cage" and "Cleaning electricity pylons" on you know where. The guys who do the cleaning deserve every penny they get.

 

[snowhead]

Have a search for "Faraday Cage" and "Cleaning electricity pylons" on you know where. The guys who do the cleaning deserve every penny they get.

The helicopter Pilot deserves more.