Red Seal Electrician Practice
DC circuitsQuestion 634 of 1506

A 48 V supply feeds three resistors in series. The drops across two of them are 18 V and 12 V. What is the voltage drop across the third resistor?

  1. 30 V
  2. 18 V
  3. 12 V
  4. 66 V
Show answer

Correct answer: 18 V

The drops add up to the supply voltage: 48 V - 18 V - 12 V = 18 V.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 5.2: Simple Series Circuits

Practice dc circuits

Questions last reviewed: 18 October 2026