Rload

Rload is a term used in electronics to denote the load resistance connected to a circuit. It represents the element that consumes power from a source, typically modeled as a resistor with a value measured in ohms (Ω). In circuit analysis, Rload is often shown as the resistor across which the output or downstream portion of the circuit is taken.

In a network described by a Thevenin equivalent, the source is an open-circuit voltage Vth in series with a resistance Rth. The voltage across the load and the current through it are given by Vout = Vth · (Rload / (Rth + Rload)) and Iload = Vth / (Rth + Rload). The load power is Pload = Vout^2 / Rload = Iload^2 · Rload. In alternating current or impedance analyses, the load is represented as Zload. For a purely resistive load, Zload = Rload, and the same voltage-divider relationships apply with real arithmetic.

Maximum power transfer occurs when Rload equals Rth, according to the maximum power transfer theorem. This condition optimizes power delivery to the load but may be undesirable for efficiency or regulation reasons in real designs, where a lower current draw or higher efficiency is preferred.

Rload is widely used in simulations, measurements, and testing. In SPICE and other circuit simulators, it is the parameter assigned to a resistor labeled as the load. It can also model real devices’ input or drain impedances and serves as a simple, practical representation of a downstream load in both analog and mixed-signal contexts.