What is the measured voltage of the series-parallel circuit between terminals A and B?

• A. 3.0 volts
• B. 1.5 volts
• C. 4.5 volts
• D. 2.0 volts

Answer: (A)

Voltage in series and parallel parts of a circuit is all about how the resistors share the supply. When you have a simple voltage divider made of two equal resistors in series across a source, each resistor drops half of the source voltage. The node between them sits at the midpoint, so the voltage from that node to ground is half the supply.

In the circuit you’re looking at, the measurement between A and B sits across that equal-divider portion, so it reflects half of the source voltage. If the source is 6 volts, that half is 3.0 volts, which is why the reading is 3.0 volts. The parallel branches around this divider don’t change the voltage at AB—they just affect currents in different branches while keeping AB’s voltage determined by the divider, assuming the source and resistor values stay the same.