What is the commercial unit of electric charge?

Kilowatt hour

The correct answer is Option (4) → Kilowatt hour

The commercial unit (or practical unit used in electricity billing and everyday commerce) of electric charge is the kilowatt-hour (kWh).

• Electric charge (Q) is fundamentally measured in coulombs (C), where 1 C = 1 ampere × 1 second.
• However, in commercial and household contexts, electricity consumption is measured by energy used, not charge directly.
• 1 kilowatt-hour = energy consumed when 1 kilowatt of power is used for 1 hour = 3.6 × 10⁶ joules.
• Since power (P) = V × I, and energy = P × t = V × I × t = V × Q, → kWh indirectly represents the total charge passed through the circuit for a given voltage and time.

Electricity bills charge based on kWh consumed, making it the practical/commercial unit associated with the amount of electric charge utilized.