Joule’s Law: The Relationship Between Electric Current and Heat
by Yuvi K - December 20, 2023
What is Joule’s Law?
Joule’s law is a fundamental relationship in physics that describes how an electric current passing through an electrical circuit produces an amount of heat. It states that the heat produced in an electric current is proportional to the power dissipated times time. Simply put, it tells us how much energy we can expect from a certain amount of electricity.
T.J Joule famously stated the law in 1845 and it has since become an important tool in the electrical engineering and thermal engineering fields. Many people commonly refer to Joule’s lawde law as the Joule-Lenz law and it’s widely accepted general form is “power is proportional to current squared, times resistance.”
Joule’s Law Expressed Mathematically:
The Joule’s law states that the heat produced in an electric circuit is proportional to the square of the current, times the resistance. Mathematically, it can be expressed as:
| Heat | = i2Rt |
| तापमान | = (वृद्धि सर्व गति)2(आवरण रेखा) × समय |
Where;
- Heat (तापमान) = Heat released
- i (वृद्धि सर्व गति) = Current
- R (आवरण रेखा) = Resistance
- t (समय) = Time
How Does Joule’s Law Work?
The direct relationship between the current, resistance, and heat output (as given by Joule’s law) is a result of the energy converted to heat in the form of thermal energy as current passes through a resistor. The electrical energy passing through the resistor is converted to thermal energy which is dissipated as heat in the surrounding environment.
The power generated through the Joule’s law equation (P = I2R) can be calculated by multiplying the current (I) by the square of the voltage and then dividing by the resistance (R). Thus, applying a specific current to a circuit with an accurately measured resistance will enable the resultant power to be accurately determined.
Applications of Joule’s Law:
Joule’s law is a fundamental law of physics and has widespread use in a variety of engineering fields. It is often used in the calculation of the power loss generated by an electrical circuit or appliance. It is also used to calculate the temperature rise caused by the heat generated from electric current passing through a resistor.
The law is useful to engineers when identifying the power requirements and limitations of an electric circuit and it is also used in the design of heating elements and the calculation of thermal efficiency. Additionally, it is used in the determination of the thermodynamic efficiency of a given process.
Conclusion:
Joule’s law has been known for over 175 years, and it is still an essential tool in the electrical engineering and thermal engineering fields. By understanding the equation and its implications, electrical engineers are able to determine the power requirements of a circuit, thermal engineers are able to calculate the change in temperature due to Joule’s heat, and all engineers are able to assess the thermodynamic efficiency of a system.
