SQA Higher Physics Practice Exam

Electric current is fundamentally defined as the flow of electric charge. It is measured in amperes (A) and represents the rate at which charge flows through a conductor, such as a wire. When an electric potential difference is applied across a conductor, it causes charges (typically electrons) to move, resulting in an electric current. This movement can be visualized as a flow of water through a pipe, where the amount of charge flowing per unit time is akin to the volume of water.

While potential difference, resistance, and energy per charge are related to electric circuits, they do not describe electric current itself. Potential difference refers to the difference in electric potential between two points in a circuit and is responsible for driving the current. Resistance is a measure of how much a material opposes the flow of charge. Energy per charge, also known as voltage, represents the amount of energy each charge carries. Each of these terms is crucial for understanding circuits and the behavior of electric current but does not directly define what electric current is.