Joule's First Law Formula |
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\( q \;=\; I^2 \cdot R \cdot t \) (Joule's First Law) \( I \;=\; \sqrt{ \dfrac{ q }{ R \cdot t } } \) \( R \;=\; \dfrac{ q }{ I^2 \cdot t }\) \( t \;=\; \dfrac{ q }{ I^2 \cdot R} \) |
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| Symbol | English | Metric |
| \( q \) = Heat | \(Btu\;/\;lbm\) | \(kJ\;/\;kg\) |
| \( I \) = Current | \(A\) | \(A\) |
| \( R \) = Resistance | \(\Omega\) | \(\Omega\) |
| \( t \) = Time Duration | \(sec\) | \(s\) |
Joule’s first law, also called the law of heating, states that the heat produced in a conductor due to the flow of electric current is directly proportional to the square of the current, the electrical resistance of the conductor, and the time for which the current flows. In other words, when an electric current passes through a resistive material, electrical energy is converted into thermal energy, which raises the temperature of the material. This principle is the basis for understanding the heating effects of electricity, and it is widely applied in devices such as electric heaters, fuses, and incandescent bulbs.
