At 7.15 cents per kilowatt-hour, what does it cost to leave a 75.0W light burning 24.0 hours a day?
1KWh=7.35cents
1.8KWh=
1.8×7.35=13.23cents
75W for 24 hours
=0.075 kW for 24 hours
=1.8 kW for 1 hour
=1.8 kW-h
How much would that cost?
To determine the cost of leaving a light burning for 24 hours a day, we need to calculate the total energy consumed in kilowatt-hours (kWh) and then multiply it by the cost per kilowatt-hour.
First, we need to convert the power of the light from watts (W) to kilowatts (kW). Since there are 1000 watts in a kilowatt, we divide the power by 1000:
75.0W ÷ 1000 = 0.075kW
Next, we calculate the total energy consumption by multiplying the power by the time:
0.075kW × 24 hours = 1.8 kilowatt-hours (kWh)
Finally, we multiply the total energy consumption by the cost per kilowatt-hour to find the total cost:
1.8 kWh × 7.15 cents/kWh = $0.129 or approximately 13 cents
So, it would cost approximately 13 cents to leave a 75.0W light burning for 24.0 hours a day at a rate of 7.15 cents per kilowatt-hour.