how does the drift velocity of electrons in a metallic conductor change if the length of the conductor is doubled by stretching it. PD is kept constant explain
39let v be the drift velocity
i=nqAv where n is no:of electrons and A is area of cross section
v/r=nqv
where r is the rsistance
V=rnqv this implies V=dlnqvA/A (aaplying formula for resistance)
(D IS DENSITY)
V=dlnqv =mnqv/A (writing formula for density d)
implies velocity is directly proportional to area
since n,q,v are constants so vel will become 4 times
1v= u+at
here u=0 (as electrons are moving randomly in all directions .. so vectorically u=0)
so v=at a=qE/m
E=electric field
E=V/l so v=qVt/l
here t= relaxation time(constant) .. V is constant ..
l is doubled so v is halved
39so 3 guys and 3 answers , some phy experts , conformation required!
1@ neil u r right .. i have edited my post #3 wher i had earlier taken E=Vl
but now i hav edited it ... E=V/l.... hence halved
