Battery in Space? Current Flow in Vacuum?

[Shaun]

What would happen if you took a battery into space? Would a current flow between terminals being it's in the vacuum of space?

 

[davenn]

Hi Shaun
welcome to PF

what do you think would happen and why ?

does it flow between terminals in the Earth's atmosphere ?

Dave

 

[Shaun]

Thank you :) I'm glad to be here. We'll I think on Earth no current would flow because air is some what of an insulator unless the voltage was high enough to Ionise the air "breakdown voltage" but in space there is no resistance and a potential always exists so I think it would flow :)

 

[davenn]

think about what you said about the air and the ionisation
if air is (as you say) somewhat of an insulator ...
Don't you think a vacuum ... the absence of air, would be an even better insulator ?
There isn't anything between the terminals that can be ionised, so therefore, no conductive path can form

how's that sound to you ?

cheers
Dave

 

[phinds]

,... in space there is no resistance

Why do you think this? What IS resistance in your mind?

 

[B0b-A]

The breakdown-voltage does drop as the gas pressure is lowered ,
but undergoes a steep U-turn at about 1/100th of an atmosphere ...

http://en.wikipedia.org/wiki/Paschen's_law

The vacuum of space is less than a trillionth of Earth's atmospheric pressure.

 

[sophiecentaur]

Vacuum capacitors are used in situations with very high voltages- such as in high power transmitters. A vacuum works very well for insulating capacitor plates, separated by a couple of cm. It's particularly useful because of the presence of high power RF fields which would involve losses in solid dielectric.

 

[Shaun]

Thanks for the replies everyone :) I was unaware of Paschen's Law, what if I heated up the terminal? Would that make a difference? Would thermal electron emission still take place in the vacuum of space and if so, how if space has infinite resistance?

 

[davenn]

Hi Shaun
good to see you logging back in

One example of useful Thermionic emission is in the old valve radios ( valves, sometimes called tubes)
I don't know how old you are or if you know what valves are ?'
Usually a sealed glass tube with a vacuum inside

the most basic valve is a diode usually used as a rectifier for converting AC voltage to DC voltage
it has a cathode that when a voltage is supplied to it, it heats up and emits electrons. The other part is called an anode that has a positive voltage potential on it ...
Have a look at this diagram and see if you have any questions

electrons that are emitted from the cathode don't need a medium ( say a wire) to travel through.
The will happily cross the vacuum gap being attracted by the high voltage positive charge on the anode

cheers
Dave