Current flowing through a conductor produces heat. This heat depends on quantity of current flowing through the conductor, time and resistance of the conductor.
We can write:
H α I²
H α R
H α t
By combining these three relation we get:
H α I²Rt
for I=1 Amp., R= 1 ohm and t= 1 sec.
K becomes equal to heat generated at this condition. It is found heat generated is 0.24 calorie.
∴ H=0.24 I²Rt
This is also known as Jouls Law of Heating.
Also remember. 1 Calorie = 4.2 Joul
The above video contains explanation of heating effect of current through a conductor. The equation derivation is also shown.
Why 0.24 added while breaking proportionality is clearly explained.