Question

If n, e, τ and m have their usual meanings, then the resistance of a wire of length l and cross-sectional area A is given by ______.

पर्याय

• `("ne"^2A)/(2mtaul)`

• `(ml)/("ne"^2tauA)`

• `(mtauA)/("ne"^2l`

• `("ne"^2tauA)/(2ml)`

Answer 1

If n, e, τ and m have their usual meanings, then the resistance of a wire of length l and cross-sectional area A is given by `bbunderline((ml)/("ne"^2tauA))`.

Explanation:

Drift velocity = v_d = `(eVtau)/(ml)`    ...(i)

Current = I = enAv_d    ...(ii)

Using equations (i) and (ii)

`V/I = (ml)/("ne"^2tauA)`

When m, l, n, e, `tau`, A are constant, then

`V/I = R`

= `(ml)/("ne"^2tauA)`