This document discusses measuring discharge or flow rate using a current meter. It describes how discharge is calculated as the product of flow velocity and cross-sectional area. A current meter is used to measure flow velocity by detecting the time taken to travel a given distance. The area-velocity method is then described as the most common approach, where the cross-sectional area is divided into rectangles, the velocity is measured in each, and the discharge is calculated by summing the product of area and velocity for each subsection.