A typical cost for electrical power is 0.120 per...

A typical cost for electrical power is $0.120 per kilowatthour. (a) Some people leave their porch light on all the time. What is the yearly cost to keep a 75-W bulb burning day and night? (b) Suppose your refrigerator uses 400 W of power when it's running, and it runs 8 hours a day. What is the yearly cost of operating your refrigerator?

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Key Concepts

Electrical Power

This is the rate at which electrical energy is consumed or produced and is measured in watts. Electrical power indicates how quickly energy is used, which is essential for determining consumption over time.

Energy Consumption

Energy consumption refers to the total amount of energy used by a device over a period of time. It is calculated by multiplying the power rating of the device (in kilowatts after conversion) by the number of hours it operates, resulting in a measure in kilowatt-hours (kWh).

Unit Conversion

Proper unit conversion is vital when calculating energy consumption and cost. In this context, converting watts to kilowatts (by dividing by 1000) ensures that the power is in the correct unit for computing kilowatt-hours, which is the standard unit used by power companies.

Cost Calculation

Cost calculation involves multiplying the total energy used in kilowatt-hours by the cost per kilowatt-hour. This process translates energy consumption into an estimated expense, allowing for financial budgeting based on usage.

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