Power Notes
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Electrical power is measured in watts and refers to the rate at which electrical energy flows through a circuit. Electrical energy purchased is measured in kilowatt-hours, which is the amount of power used over time. The formula for calculating power is Power (watts) equals Voltage (volts) multiplied by Current (amps). For example, a coffee maker that uses 1050 watts for 1 hour per day and electricity costs 14 cents per kilowatt-hour would cost around $4.41 per month to run.
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Power Notes
- 1. Power
- 2. Electrical Power • Rate electricity is flowing in circuit • Unit – watt (w) – Rate energy is used by an object – Converted from electrical energy to radiant or thermal
- 3. Buying electricity • Electrical energy is bought by kilowatt-hour (kWh) – Means 1 kW of power has been used in 1 hr • 1 kWh = 1000w
- 4. P=VxI Power (w) Current (A) Voltage (V)
- 5. • Example) You’re charged 14 cents per kWh. A coffee maker has a power rating of 1050 watts and is on for about 1 hour each day. How much does it cost to run this for a month? 1050 W = 1.05 kW 1.05kW * 1 hr/day = 1.05 kWh/day 1.05 kWh/day * 30days/mth = 31.5 kWh/mth 31.5 kWh/mth * $0.14/kWh = $4.41/mth
- 6. Works Cited • Hsu Ph.D., Tom. Foundations of Physical Science. 1st ed. Peabody: Cambridge Physics Outlet, 2002. 137-140. Print. • Microsoft Office PowerPoint ClipArt. 2000.