IIT JEE , AIEEE Forum - Physics , Electricity

city_gal1234

Give reasons

The electron drift speed is estimated to be only a few mm/s . How can such a small speed account for instantaneous current
Is a wire carrying current charged ? Why or why not ?

spideyunlimited

I = dq / dt
dq is small amount of charge flowed through conductor through some time t.
now if more electrons flow together the charge will be more, even if the drift velocity is very small.
that is why current of different values is obtained.

bhuvana89

ans 1 )

whenever u switch on.....current flows instantly despite the low value of drift velocity....

this is because when u switch on , electric field is created instantly which creates a local electron drift......the electrons of a region collide wid neighbouring ones and so on.......so it takes time for
the current to be steady...(few seconds).......even though current flow is instant...
also it is important to note that current flow doesn't mean that electrons travel from one end to the other end of conductor...

spideyunlimited

yes the last line of bhuvana89 's answer is quite important. current flow doesnt mean electrons have to travel a certain distance, they just have to be moving.

bhuvana89

ans 2)

no
it is not charged.........the electrons which flow out from 1 end .....enter through the other end........

but i think charge distribution may change though.....

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