What do n, q, and v represent in the current formula I=nqAv?

[Yapper]

Current = I = nqAv, HELP

I found this formula for current, I, know A is area, but I don't know what nq and v are... Can anyone help me?

 

[vincentchan]

v=speed of electron
n= number of FREE electron per unit volume
q= charge of electron
A= cross section area

 

[Yapper]

oohhhhh ok, q is a constant, makes sense... Thanks a lot. V varies with the material its flowing through? And how do u calculate n??

 

[da_willem]

oohhhhh ok, q is a constant, makes sense... Thanks a lot. V varies with the material its flowing through? And how do u calculate n??

You can try to find out the density of lattice ions, and multiply this by the number of conduction electrons they supply. In case of a solid you could look up the lattice spacing and how many atoms are in it. Or you could use the mass density and their molar masses.

 

[vincentchan]

what grade r u in? this should be easy if you have taken some very basic chemistry course...look up the density of the meterial, also the mass of atom...you can easily find out the number of atom per unit volume from the information above... then multiply by the number of free electron per atom...

 

[Yapper]

ok, thanks for the help. I had forgotten what was meant by free. But i got it now, thanks

 

[poolwin2001]

v is the drift velocity of the electron.i.e the velocity acquired by the electron due to thermal energy.