Bridge Difference Three-Row Scan - Electronic Circuits II Step by Step

A bridge voltmeter reads the exact difference between two divider node voltages. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

A bridge starts with two divider outputs

The left branch stays fixed. The right branch changes, so the bridge voltmeter reads the exact node-voltage difference.

V_{\text{bridge}}=\left|V_{\text{left}}-V_{\text{right}}\right|

The difference grows as the right node drops

Read each row as left output, right output, then absolute difference. The balanced row is allowed to be exactly zero.

\begin{array}{c|c|c}V_{\text{left}}&V_{\text{right}}&V_{\text{bridge}}\\8\ \text{V}&8\ \text{V}&0\ \text{V}\\8\ \text{V}&\tfrac{36}{5}\ \text{V}&\tfrac{4}{5}\ \text{V}\\8\ \text{V}&6\ \text{V}&2\ \text{V}\\\end{array}

The final row exceeds one volt

For the rendered row, the bridge difference is 2 volts, above a one-volt strict threshold.

2\ \text{V}>1\ \text{V}