How much does it cost to have a light on for 1 hour?

The cost of having a light on for 1 hour depends on the wattage of the bulb, the electricity rate in your area (measured in cents per kilowatt-hour, or $ per kWh), and how efficient the light bulb is.

1. Calculating the Cost for Different Types of Bulbs

We'll calculate the cost for three common types of bulbs: Incandescent bulbs, LED bulbs, and CFL (Compact Fluorescent Lamp) bulbs.

Example 1: Incandescent Bulb (60W)

  • Wattage: 60 watts (0.06 kW)
  • Electricity Rate: $0.12 per kWh (U.S. average rate)
  • Duration: 1 hour

Step 1: Convert watts to kilowatts

Since electricity is billed in kilowatt-hours (kWh), divide the wattage by 1000:

60 watts÷1000=0.06 kW60 \, \text{watts} \div 1000 = 0.06 \, \text{kW}

Step 2: Calculate the cost

Multiply the kWh by the electricity rate to get the cost for 1 hour:

0.06 kW×0.12 USD/kWh=0.0072 USD0.06 \, \text{kW} \times 0.12 \, \text{USD/kWh} = 0.0072 \, \text{USD}

So, it costs approximately 0.7 cents to run a 60W incandescent bulb for 1 hour.

Example 2: LED Bulb (9W)

  • Wattage: 9 watts (0.009 kW)
  • Electricity Rate: $0.12 per kWh
  • Duration: 1 hour

Step 1: Convert watts to kilowatts

9 watts÷1000=0.009 kW9 \, \text{watts} \div 1000 = 0.009 \, \text{kW}

Step 2: Calculate the cost

0.009 kW×0.12 USD/kWh=0.00108 USD0.009 \, \text{kW} \times 0.12 \, \text{USD/kWh} = 0.00108 \, \text{USD}

So, it costs approximately 0.1 cents to run a 9W LED bulb for 1 hour.

Example 3: CFL Bulb (13W)

  • Wattage: 13 watts (0.013 kW)
  • Electricity Rate: $0.12 per kWh
  • Duration: 1 hour

Step 1: Convert watts to kilowatts

13 watts÷1000=0.013 kW13 \, \text{watts} \div 1000 = 0.013 \, \text{kW}

Step 2: Calculate the cost

0.013 kW×0.12 USD/kWh=0.00156 USD0.013 \, \text{kW} \times 0.12 \, \text{USD/kWh} = 0.00156 \, \text{USD}

So, it costs approximately 0.16 cents to run a 13W CFL bulb for 1 hour.

Cost Comparison

Bulb Type Wattage Cost for 1 Hour
Incandescent 60W 0.7 cents
LED 9W 0.1 cents
CFL 13W 0.16 cents

Conclusion

  • LED bulbs are the most energy-efficient option and are the least expensive to operate for just 1 hour.
  • Incandescent bulbs are the most expensive to run, consuming more electricity and thus costing more to operate.
  • CFL bulbs are a middle ground, providing decent energy savings compared to incandescent bulbs, but not as much as LEDs.

Switching to LEDs can significantly reduce your energy consumption and lower your electricity bill in the long term.

If you need help with specific bulb types or want to calculate the cost for other appliances, feel free to ask

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