Current through a resistor produces heat – useful in kettles, toasters and fuses, wasteful in cables and chips. Doubling the current quadruples the heat.
How to use the Joule Heating Calculator
- Current I
- Resistance R
- Time t
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the current, resistance and time.
Tips
- Use absolute temperature (K) in gas laws and efficiency formulas.
- Temperature differences are the same in K and °C.
- Heat = mass × specific heat × temperature change when no phase change occurs.
- Phase changes need latent heat at a constant temperature.
Common mistakes to avoid
- Using °C in pV = nRT.
- Forgetting latent heat during melting or boiling.
- Confusing heat capacity (J/K) with specific heat (J/(kg·K)).
Inputs explained
| Field | What to enter |
|---|---|
| Current I | Units: A, mA, µA, kA |
| Resistance R | Units: Ω, kΩ, MΩ, mΩ |
| Time t | Units: s, ms, min, h, days |
What each result means
- Heat produced Q = [Current I]^2×[Resistance R]×[Time t]
- Power = [Current I]^2×[Resistance R]
Example values
How the main result changes when Current I changes and everything else stays at the example values above:
| Current I (A) | Heat produced Q (J) |
|---|---|
| 2.5 | 3,750 |
| 3.75 | 8,437.5 |
| 5 | 15,000 |
| 6.25 | 23,437.5 |
| 7.5 | 33,750 |
| 10 | 60,000 |
Formula
Q = I²·R·tWorked example
Inputs — Current I: 5 A; Resistance R: 10 Ω; Time t: 60 s.
Results — Heat produced Q = 15,000 J; Power = 250 W.
Key terms
- Joule heating
- Heat from current through resistance.
Frequently asked questions
Why does heat depend on I²?
Power = I²R – current enters twice.
Why are transmission lines high voltage?
Lower current means much less Joule heating loss.
What is Joule heating used for?
Heaters, fuses, incandescent lamps, soldering irons.
Is it the same as ohmic heating?
Yes.
What formula does the Joule Heating Calculator use?
Q = I²·R·t.