In a parallel circuit with a constant voltage power supply, the voltage drop across each branch is __________.

• A. equal to the power supply voltage
• B. equal to the branch resistance
• C. equal to the current
• D. zero

Answer: (A)

In a parallel circuit, all branches are connected directly across the same two nodes, so they share the same voltage. With a constant-voltage power supply, the potential difference across every branch equals the supply voltage. This means the voltage drop across each branch is the same as the source voltage. The current in each branch, however, depends on that branch’s resistance via Ohm’s law (I = V/R), so different branches can draw different currents even though they all see the same voltage. The other options don’t fit because the voltage drop isn’t set by the branch resistance or by the current, and it isn’t zero in a normal loaded circuit.