what will be the approximate cost in cents of running a 10 watt light for one week
The correct answer and explanation is:
Correct Answer:
Approximate cost in cents: 28 cents
To calculate the cost of running a 10-watt light for one week, we begin by determining how much energy it consumes over that time and then convert it into a cost using the average electricity rate.
A watt is a measure of power, and when used over time, it becomes watt-hours, which is a measure of energy.
The light runs for 1 week, which is:
- 7 days × 24 hours/day = 168 hours
Next, multiply the power by time to find energy used:
- 10 watts × 168 hours = 1680 watt-hours
- Convert watt-hours to kilowatt-hours (kWh) since electricity is billed in kWh:
- 1680 watt-hours ÷ 1000 = 1.68 kWh
Now use the average electricity cost. In many countries like the United States, the average residential electricity cost is around $0.17 per kWh, which is 17 cents per kWh.
Multiply the energy used by the cost per kWh:
- 1.68 kWh × 17 cents = 28.56 cents
This rounds to approximately 28 cents to run the 10-watt light for one week.
This result shows how energy-efficient a 10-watt light is. Such lights are often LED bulbs. Running one for an entire week nonstop costs less than a single coin. This low cost is one of the reasons LED lights are so popular. They provide good brightness while keeping electricity bills down. If many lights are used, the total cost can still grow, so using efficient lights and turning them off when not needed helps save money and energy.