How it works
This circuits quiz has 35 questions in two sets: what the bulbs do in a series or a parallel circuit when one is removed or a switch is opened, and Ohm's law sums with whole-number answers.
Read the full guide
Two sets
Series or parallel also adds cells in series and in parallel, and puts two switches in one circuit. Ohm's law asks for a voltage, a current or a resistance, for one resistor and for two in series or in parallel.
Circuits in words
Each quiz circuit is described in words: how many bulbs, how they are joined, which switch is open. No sum needs a calculator.
- Two switches in series work like AND: both must be closed. Two in parallel work like OR: one is enough.
- Pick the form that leaves the unknown alone: V = I × R, I = V ÷ R or R = V ÷ I.
Questions and answers
What is the difference between a series and a parallel circuit?
In a series circuit the parts sit one after another on a single path, so the same current passes through each. In a parallel circuit each part has its own path to the battery and has the full battery voltage across it.
What happens if one bulb goes out in a series circuit?
The single path is broken, so the current stops and every bulb goes out. In a parallel circuit the other bulbs stay lit.
What is Ohm's law?
The current through a conductor is directly proportional to the voltage across it. Written with resistance, V = I × R: volts equal amperes times ohms. It is named after Georg Ohm, who published it in 1827.
How do you find the total resistance of a circuit?
For resistors in series, add them: 4 ohms and 6 ohms make 10 ohms. For two resistors in parallel, multiply them and divide by their sum: two 6-ohm resistors make 3 ohms, less than either alone.