Application of Heating Effect of Electrical Current
We have all used a water-heater or an iron box at least once
Both of them have a common thing in them, that is they can generate heat
They produce heat, only when electric current is passing through them
And James Prescott Joule was the first person who saw this effect of generation of heat when current is passing through a substance
So, what happens is whenever electric current or electric charges try to flow through a substance
That substance will oppose the flow of charges as they have resistance
By doing so, the resistors will consume the electrical energy the charges have and convert it into another form like heat and light
Joule observed this and gave a law to explain this production of heat due to current which is now known as Joule's law of heating
It is given by the formula
where, Q = Heat Energy released,
I = Electric current in the wire,
R = Resistance of the wire,
t = time for which the circuit is on
So we can say that more heat is generated when the current and the resistance are high. It is also dependent on the time for which the circuit was on
The Heating effect of electric current has many practical applications
One such application is a light bulb
One such application is a light bulb (that is the production of light)
Bulbs have a filament(coil-like structure) inside them and current passes through this element
This filament is made of tungsten which has a very high resistance
So, as soon as the current passes through it, the filament heats up, and this produces light. So, this is how electrical energy is converted to light energy
The heat that is produced in the filament is more because of the high resistance of the filament which is why the bulb lights up
Moving on, there are some appliances where electrical energy is converted to heat energy
Let us take the example of an iron
The iron has a coil that has high resistance
When current passes through this coil, heat is produced because of which the plate gets heated up
So here electrical energy is converted into heat energy. This is how we can iron our clothes
Now, if we talk about a steam iron
Here, the water is converted into steam because of the heat produced by the coil
Other common examples for the heating effect would be an immersion rod and a fan heater
They also consist of coils that are heated up once electrical energy passes through them
REVISION
Whenever current flows through wires, some electrical energy is transformed into thermal energy called Joule heating
And the formula to calculate the heat released is
So more the current, resistance and the time for which the circuit is on, the more the heat is generated
Using this law, electrical energy is converted to heat energy in appliances like electric heaters and electric iron
Similarly, electrical energy is converted to light energy in appliances like an electric bulb