Question

Define 1 kilowatt-hour (kWh) and state its relationship with Joules.

Hint:

{1 kWh} is commonly called {one unit of electricity} used in electricity bills.

Answer 1

Concept: Electrical energy consumed by appliances is commonly measured in kilowatt-hour (kWh). It is a practical unit of electrical energy used in households and electricity billing.
Step 1:Definition of 1 kWh} 1 kilowatt-hour (kWh) is defined as the amount of electrical energy consumed when an electrical appliance of power 1 kilowatt operates for 1 hour. \[ 1 \, \text{kWh} = 1 \, \text{kW} \times 1 \, \text{hour} \]
Step 2:Conversion into Joules} \[ 1 \, \text{kW} = 1000 \, \text{W} \] \[ 1 \, \text{hour} = 3600 \, \text{s} \] Using the formula for energy: \[ E = P \times t \] \[ E = 1000 \times 3600 \] \[ E = 3,600,000 \, \text{J} \] \[ E = 3.6 \times 10^{6} \, \text{J} \]
Step 3:Final relation} \[ \boxed{1 \, \text{kWh} = 3.6 \times 10^{6} \, \text{J}} \]