Question

1 KWh is equal to :

• A. $3.6 \times 10^6$ J
• B. $3.6 \times 10^9$ J
• C. $3.6 \times 10^{12}$ J
• D. $3.6 \times 10^{7}$ J

Hint:

Remember that 1 kilowatt-hour (KWh) is a unit of energy, and it represents the energy consumed by a device with a power of 1 kilowatt operating for one hour. The conversion to Joules involves multiplying kilowatts by 1000 (to get watts) and hours by 3600 (to get seconds), since 1 Watt = 1 Joule/second.

Answer 1

The Correct Option is A

Step 1: Understand the units involved.
KWh (Kilowatt-hour) is a unit of energy. It is commonly used to measure electrical energy consumption.
J (Joule) is the standard international (SI) unit of energy. Step 2: Break down KWh into fundamental units. 1 KWh means 1 kilowatt operating for 1 hour.
1 kilowatt (KW) = $1000$ watts (W)
1 hour (h) = $60$ minutes $\times$ $60$ seconds = $3600$ seconds (s) The relationship between power, energy, and time is: Energy = Power $\times$ Time. So, 1 KWh = 1 KW $\times$ 1 h. Step 3: Convert KWh to Joules.
Substitute the values from Step 2:
1 KWh = $1000$ W $\times$ $3600$ s
Recall that 1 Watt (W) = 1 Joule per second (J/s).
So, 1 KWh = $1000$ (J/s) $\times$ $3600$ s
1 KWh = $3,600,000$ J
Step 4: Express the result in scientific notation.
$3,600,000$ J can be written as $3.6 \times 10^6$ J.
Step 5: Compare the result with the given options.
The calculated value $3.6 \times 10^6$ J matches option (1).
\[ \mathbf{(1) \quad 3.6 \times 10^6 \, J} \]