What is the opposition to current flow called?

The term for the opposition to current flow in an electrical circuit is resistance. Resistance is a fundamental property of materials that impedes the movement of electric charge. It determines how much current will flow when a certain voltage is applied across a component. The higher the resistance, the less current will flow for a given voltage according to Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R).

In practical applications, resistance is crucial for understanding how various components, such as resistors, work in circuits, aiding in the control and manipulation of electrical energy. Knowing how to calculate and measure resistance helps in designing efficient circuits and for troubleshooting purposes.