What is the commercial unit of electrical energy? Convert it into joule. What is the other name of the commercial unit? What is meant by a parallel combination of resistors? Deduce an expression for the equivalent resistance when two resistor are connected in parallel.
Commercial unit of electrical energy is the unit in which all our household electrical consumptions are measured.
1 kWh=1000 watt × 3600 seconds
The commercial unit of current is kilowatt hour (kWh).
In parallel combination of resistors the voltage across all the resistors are constant but the total current is divided in all the branches.
As the current is given by
So, in the circuit
Hence, in parallel connection the reciprocal of equivalent resistance is equal to the sum of reciprocal of individual resistances.