Understanding Resistance in Electrical Circuits
Source resistance refers to the internal resistance of a power source, such as a battery or generator.
It arises from the materials and construction of the power source, limiting current flow.
It causes a voltage drop when current flows, reducing the effective voltage at the output.
Typically measured in ohms using techniques like the open-circuit voltage method.
High source resistance leads to poor voltage regulation, causing output voltage to vary with load.
It dissipates energy as heat, reducing overall efficiency of the circuit.
Increases total resistance in the circuit, thereby limiting the maximum current delivered.
In a battery-powered device, high source resistance can cause dimming of lights under heavy load.
Load resistance is the resistance of the external device or component connected to the power source.
It determines the amount of current drawn from the source and the power consumed.
Load resistance can change based on the device's operation, such as in variable resistors or motors.
Measured directly using an ohmmeter when the circuit is disconnected from the source.
Lower load resistance increases current draw, potentially overloading the source.
Optimum load resistance maximizes power transfer, as per the maximum power transfer theorem.
Higher load resistance results in higher voltage across it, affecting device operation.
In an amplifier circuit, mismatched load resistance can distort the output signal.