Maximum Power DC

Maximum Power Transfer (DC)

Step 1: Derivation

Consider a Thevenin equivalent circuit:

Vth → Rth → RL

The circuit current is

I = Vth / (Rth + RL)

Power delivered to the load is

P_L = I² RL

Substitute the current expression

P_L = (Vth² RL) / (Rth + RL)²

To find the maximum power, differentiate with respect to RL and set to zero:

dP/dRL = 0

This gives the condition

RL = Rth

The maximum power becomes

Pmax = Vth² / (4Rth)

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Step 2: Interactive Simulator

Enter circuit parameters and move the load resistance slider to observe how the power changes.

Vth (Volts)

Rth (Ohms)

Load Resistance RL (Ohms) 5 Ω