Unloaded Divider Node - Electronic Circuits II & III: Decision Networks and Interfaces Step by Step

An unloaded-divider-node scan computes the node voltage V_out = V_in * R_b / (R_t + R_b) before any load is attached, here the lower 6 ohm of a 3 + 6 ohm chain giving 8 V. The arithmetic is exact only for the stated source voltages, resistances, currents, output voltages, and rows in the ideal resistor, ideal supply, unloaded model. Real dividers add resistor tolerance, source resistance, finite load impedance, input threshold spread, temperature drift, meter/probe calibration limits, finite precision, and measurement uncertainty.

A divider output is a checked node voltage before anything else is attached to it. 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 divider splits the source voltage

The top resistor is 3 ohm and the bottom resistor is 6 ohm.

R_{\text{total}} = 3\ \text{ohm} + 6\ \text{ohm}

The output is the lower drop

The checked current is fractional, so the lower resistor has 8 volts across it.

V_{\text{out}} = I R_{\text{bottom}} = 8\ \text{V}