Skip to main content

Mathematics for Physics

34 Current

A rate of electric charge flow past a point that is used to measure how much charge passes through a wire or region per unit time.

The definition of current. Current is the rate at which charge passes a point. This principle is used to assign a single number \(I\) to the flow in a wire.

The definition of current is

\[ I = \dfrac{dQ}{dt} \]

where

  • \(I\) is the electric current.
  • \(Q\) is the charge that has passed the point.
  • \(t\) is time.

The charge delivered by a steady current. A steady current moves a charge proportional to the elapsed time. This principle is used to compute the total charge delivered by a constant current.

The charge delivered by a steady current is

\[ Q(t) = It \]

where

  • \(Q(t)\) is the charge that has passed by time \(t\).
  • \(I\) is the steady current.
  • \(t\) is time.

Note: Also called electric current.