Unbalanced Bridge - Electronic Circuits II & III: Decision Networks and Interfaces Step by Step

An unbalanced bridge turns a resistor change into a voltage difference between the two divider nodes. The 8 V, 6 V, and 2 V ledger is exact for the stated ideal parts and meter; real measurements include tolerance, contact resistance, source variation, meter loading, noise, and calibration limits.

Changing one resistor changes one divider node and creates an exact bridge voltage. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Changing one resistor changes the right node

The left node remains 8 volts, but the right node is now 6 volts.

V_{\text{left}} = 8\ \text{V},\quad V_{\text{right}} = 6\ \text{V}

The bridge meter reads the difference

The exact bridge difference is 2 volts.

V_{\text{bridge}} = 2\ \text{V}