How much would it cost to operate a 100 watt light bulb 8 hours a night for 30 days?
The correct answer and explanation is:
To calculate the cost of operating a 100-watt light bulb for 8 hours a night over 30 days, we need to follow these steps:
Step 1: Calculate the energy consumption per day.
A 100-watt light bulb uses 100 watts of power every hour. To find out how much energy the bulb uses in one day (8 hours of operation), we multiply the wattage by the number of hours. Energy per day=100 watts×8 hours=800 watt-hours(Wh)\text{Energy per day} = 100 \, \text{watts} \times 8 \, \text{hours} = 800 \, \text{watt-hours} (Wh)
Step 2: Calculate the energy consumption for 30 days.
Now, we calculate how much energy is used over 30 days. Since the bulb uses 800 Wh per day, we multiply this by 30. Energy for 30 days=800 Wh/day×30 days=24,000 Wh=24 kWh (kilowatt-hours)\text{Energy for 30 days} = 800 \, \text{Wh/day} \times 30 \, \text{days} = 24,000 \, \text{Wh} = 24 \, \text{kWh} \, (\text{kilowatt-hours})
Step 3: Determine the cost of electricity.
Next, we need to know the cost of electricity per kilowatt-hour (kWh). Electricity rates vary by region, but the average cost of electricity in many areas is about $0.12 per kWh. You can check your local utility rates to get a more accurate value. For this example, we will use $0.12 per kWh. Cost=24 kWh×0.12 USD/kWh=2.88 USD\text{Cost} = 24 \, \text{kWh} \times 0.12 \, \text{USD/kWh} = 2.88 \, \text{USD}
Conclusion:
The cost to operate a 100-watt light bulb for 8 hours each night for 30 days would be approximately $2.88.
This calculation assumes that the electricity rate is constant, and it reflects just the cost of running the light bulb, not any additional fees or taxes from the utility company.