Ohm’s law: find the voltage — Electronics for kids

Remember

V on top — “in the V-I-R triangle, V = I × R”

1. V = I × R (volts = amperes × ohms).
2. Change mA to A first: 20 mA = 0.02 A.
3. Example: 0.02 A × 220 Ω = 4.4 V.

Use it for: Physics lessons on Ohm’s law, checking a circuit plan and working out the voltage across a resistor.

Worked example: 🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? → 6

✏️ Practice

Work it out in your head or on paper, then tap your answer — or type it and press Check. Stuck? Press “Show me how”.

🏁 Lesson 12 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.

🏅 Sign in with Google to earn the 🔺 Ohm Triangle Pro badge when you pass — and a certificate when you finish all 10 lessons of Part 2 · Components and Ohm’s law. You can still take the test without signing in.

🖨️ Electronics Worksheet: Ohm’s Law – Find the Voltage

• Worksheet set 1 (PDF)
• Worksheet set 2 (PDF)
• Worksheet set 3 (PDF)