Electronics 101: Power of Joule’s Law

Joule heating, also known as resistive, resistance, or Ohmic heating, is the process by which the passage of an electric current through a conductor produces heat. So this heat is important for us to have a resistor large enough to resist any meltdown. Let discuss on Joule’ Law.

History of Joule’ Law

1. Early 1800s, an abstract in the Proceedings of the Royal Society, by James Prescott Joule.
2. The law suggested that heat could be generated by passing an electric current through a wire.
3. Joule immersed a length of wire in a fixed mass of water and measured the temperature rise due to a known current flowing through the wire for 30 minutes.
4. Joule came up with an equation that give power values, it is Joule’s Law.
   • P = V x I
   • Power (in watts) equals the voltage (in volts) across a component times the current (in amps) passing through that component.
   • The equations applied to every electronic component, whether it’s a resistor, light bulb, a capacitor.

Joule’s Law formula (amount of heat)

Joule’s law formula is: Q = I² . R . t, where:

Joule law

1. Q is the amount of heat, in Joules (J)
2. I is the electric current that flows through the wire, in amperes (A)
3. R is the value of the electrical resistance of the wire, in ohms (R)
4. t is the amount of time that current passes through the wire, in seconds (s).

Using Joule’s Law to choose components

1. Lamp, diodes and other components also come with maximum power ratings.
2. If these components perform at power levels higher than their ratings, but it seems damaged.
3. Hence, we will consider maximum possible powder, that can handle the circuit.
4. When you select the part, and voltage across the part and multiply those quantities
5. Select power rating that exceeds that estimated maximum power.

Joule and Ohm: Combine Together

1. You combine Joule’s Law and Ohm’s Law to derive equation to help to calculate power for resistive components.
   1. Ohm Law: V = IxR
   2. Joule Law: P = (IxR)x I = I (power of 2) R
2. To get the voltage, replace by P = V x V/R = V (power of 2) /R

Finally, we have 2 electric law that allow us to follow that our components will not damage.