The study workshop · Level 2

One step. One circuit.

Electrical revision at your pace. Five questions, clear working and space to try again. Allow 15–20 minutes.

Quick recap — open before you practise

1. Convert, then rearrange

1 A = 1,000 mA. Start with V = I × R. Divide both sides by I to get R = V ÷ I.

Example: 12 V ÷ 0.5 A = 24 Ω.

2. Follow the paths

Series: same current; add resistances. Parallel: same voltage across each branch.

Two 10 Ω resistors: 20 Ω in series, 5 Ω in parallel.

3. Protection has conditions

An MCB rating alone cannot tell you its operating time. Use the actual current and the specific device’s time–current curve.

Schneider Electric: breaker characteristics

Source checked 26 September 2026.

Choose your focus

Starting fresh clears this set. Answers stay in this session only.

Question 1 of 5 · Protection concepts

Rating versus threshold

A 20 A MCB carries 20 A. Must it immediately trip just because it reaches that value?

Ideal resistor circuits for study. Protection questions practise concepts; permitted disconnection times require the relevant circuit, earthing arrangement and current course guidance.