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Ohm’s law can be turned round. To find the current, divide the voltage by the resistance: I = V ÷ R. To find the resistance, divide the voltage by the current: R = V ÷ I. A 6 V supply across a 12 Ω resistor gives 6 ÷ 12 = 0.5 A. To get the answer in mA, multiply the amperes by 1000.
✓ You passed this lesson’s test.
Cover what you want — “cover I in the triangle to get V ÷ R; cover R to get V ÷ I”
Use it for: Physics problems on Ohm’s law, choosing a resistor and checking how much current a part takes.
Work it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.
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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 🧮 Current Calculator 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.
Why does it work? When should you use it? Ask in English, मराठी or हिंदी.
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