Potential Difference and Current?

Question

Why does the magnitude of current depend on potential difference (i.e. - greater potential, greater current)?

- I understand that current is the rate at which charge passes through a conductor.
-And, I understand that the potential difference is the basically how much work (energy) per unit charge is needed to move a charge from one point to another.

But, is there an explanation as to why greater potential difference means greater current?

Answer 1

In a conductor of length L and A sectional area, charge e flows

current (I) = rate of flow of charge= Q / t
= n *e* (area*length) / t = n*e*A (length/time)
= n*e*A (drift velocity)
= n*e*A* vd (here n=change/volume) ...(1)

Gain in Kinetic energy of charge = (1/2)*m*vd^2 =
work done on charge by battery = V * e

(1/2)*m*vd^2 = V*e >>>> vd = sqrt (2 V e /m) put in (1)


I = n e A * sqrt (2 V e /m)

Now more is potential difference V, more is I current

I proportional to sqrt (V)

Answer 2

Compare to water travelling in pipes. The battery is the pump. The potential difference is the pressure. Increasing the pressure means you can force more water through the pipes per second.

Answer 3

Ohm's low : V=I*R, so I=V/R

Current depend on both V and R
As V increases, so does I (for constant R)
However, for constant V, as R increases, I decreases