Joules Law

Introduction

Energy and work are measured in joules. By applying a force of one newton over a distance of one meter, an object is made to work (or to be energized). One joule is produced when an object is subjected to a force of 1 N and moves 1 m. Newton meters are used to measure it. The exact equivalent of heat is produced each time mechanical force is applied. The heat generated in any electrical component varies directly to the squared current, the resistance, and the duration of the current's flow, as per Joule's law of heating.

What is Joule?

Joules are units of measurement for both energy and work. An object is made to work by applying a force of one newton over a distance of one meter. When 1 N of force is applied to any object and the object moves one meter, the product is one joule. It is measured in Newton meters. Every time mechanical force is applied, an exact equivalent of heat is obtained.

$$\mathrm{1\:J = 1\:N \times 1\:m}$$

Joule's Law of Heating

As per Joule's law of heating, the heat generated in any electrical component varies directly with the squared current, the resistance, and the duration of the current's flow.

Let's look at the equation

$$\mathrm{P=I^{2} R}$$

This equation was discovered empirically by James Joule, which means that he examined some data, made measurements, and observed the phenomenon. Measurements of power, current, and resistance resulted in this conclusion. Therefore, this equation was not derived from mathematical calculations. It was discovered empirically, and he stated that the power dissipated by a resistor varies directly to the squared current

We simply mean that current is flowing through the resistor when we say "power dissipated by the resistor". I is the current that passes through the resistor, and it heats up. Think about this heat coming from a resistor, flowing out into the air around it, dispersing, and ultimately disappearing. It does not vanish from the universe, but it scatters and becomes unusable. According to Joule, the power dissipated by a resistor is proportional to the current squared. In the equation, the power is determined by the square of the current I.

Interestingly, ohm's law, which we also discussed in V=IR, was also discovered empirically. Looking at data in the real world revealed both of these findings. Heat is produced when current flows through a resistor. The resistor's energy is completely converted into heat. Joule heating is the process of converting electrical energy to heat. Joule heating occurs when a resistance element in an electric circuit is heated. These equations represent the theory behind any electrical device designed to generate heat, such as an electric heater or a toaster. A toaster contains a heating element, and when we press the little device down, it becomes hot.

Power is energy over time.

$$\mathrm{P=\frac{Energy}{Time}}$$

$$\mathrm{Energy=Power \times Time}$$

and $\mathrm{P=I^{2} R}$

Putting the value of power

$$\mathrm{Energy=I^{2}\:RT}$$

$$\mathrm{H=I^{2}\:RT }$$

Where H= heat.

Joule Heating Power Equation for AC and DC

As per Joule's law of heating, the amount of heat produced in any electrical component directly varies with the square of the current, the resistance, and the amount of time the current is flowing. The product is one joule when 1 N of force is applied to any object and the object moves one meter. It is expressed in Newton meters.

$$\mathrm{P=\frac{Energy}{Time}}$$

$$\mathrm{Energy=Power \times Time}$$

and $\mathrm{P=I^{2} R}$

Putting the value of power

$$\mathrm{Energy=I^{2}\:RT}$$

$$\mathrm{H=I^{2}\:RT }$$

Where H= heat.

Application of Joule's Law of Heating

Electric Fuse

An electrical fuse is a small wire with not so high melting point manufactured of a tin alloy. The fuse wire is linked to the electrical appliances in series. When the electric current exceeds the max value, the fuse wire is heated to a temperature above its melting point, and the electrical circuit is cut off. The temperature at which the wire is heated varies directly to the squared current and varies inversely to the cube of the radius, so the temperature is determined by the current flowing through the wire and its radius, regardless of its length. Other applications are:-

• Electric Bulb

• Electric Heater

• Electric Iron

• Electric Geyser etc.

Apparatus for measuring the mechanical equivalent of heat

Conclusion

In joules, energy and work are measured. An object can be made to move by applying a force of one newton over a distance of one meter. When any object is subjected to a force of 1 N and moves 1 m, one joule is produced. It is measured in Newton meters. When a mechanical force is applied, the exact equivalent of heat is produced. As per Joule's law of heating, the amount of heat produced in any electrical component directly varies with the square of the current, the resistance, and the amount of time the current is flowing. In this article we have learned about what is joule's law, the joule law of heating or heating effect of current, Joule heating power equation for AC and DC, the application of joule law of heating, and some FAQs.

FAQs

Q1. What are the variables that affect Joule's heating law?

Ans: Joule's law of heating states that the amount of heat generated in a wire is directly proportional to the square of the current, the wire's resistance, and the length of time the current is allowed to flow through the circuit.

Q2. Which device doesn't follow the heating law of Joule?

Ans: Electric fans are not based on Joule's Law, unlike other well-known devices like the electric iron, heater, and light bulb.

Q3. Is the effect of joules heating reversible?

Ans: The heating effect of the joule is a permanent phenomenon. That is, if we supply current to a resistor in one direction, the resistor will heat up. By switching the current's direction, however, we are unable to cool the resistor. Therefore, this process cannot be reversed.

Q4. How much Joule's heating can an ideal insulator produce?

Ans: We are aware that an ideal insulator conducts heat and electricity poorly. As a result, since it does not conduct electricity, no heat is generated through it.

Q5. How does Joule heat change as resistance changes, both positively and negatively?

Ans: The voltage squared divided by the resistance determines the joule heating. This means that lower resistances and higher voltages both significantly increase the amount of heat produced.

Q6. Why does excessive current generate heat?

Ans: As electric currents flow through resistive components in a circuit, heat is produced. A conductor's resistance determines how much heat is produced as current flows through it. As a result, heat is inevitably produced by electric current as it flows through a conductor.

Q7. Does electricity produce heat?

Ans: Volts typically travel outside the wire and around the amps. As a result, amps will produce heat because the atoms and valence electrons create different levels of resistance, whereas volts typically won't. However, you won't feel the heat rise if you use wire that is thick enough.