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Ohm’s law.

Calculate current and power from voltage and resistance.

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R+I = 0.12 AV = 12 V
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01 / QUESTION

With 12 V across 100 Ω, the current is:

I = 12 ÷ 100 = 0.12 amperes.

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How the calculation works

I = V ÷ R and P = V × I for an ideal ohmic resistor.

KEY FORMULAI = V ÷ R and P = V × I for an ideal ohmic resistor.
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Worked example

With 12 V across 100 Ω, current is 0.12 A (120 mA) and the resistor dissipates 1.44 W.

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Before you rely on this result

This assumes constant resistance. It does not model AC motors or reactive loads.

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Informational tool. It does not replace testing, measurement or professional advice when needed.

04 /

Frequently asked questions

Why does it show power in watts?+

Resistors dissipate electrical energy as heat; check the component’s rated power.

What happens when resistance is zero?+

The formula would divide by zero and would not represent a safe real-world condition, so it is rejected.