Work, Energy and Power

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Power is

• the rate of doing work.

• the rate of energy conversion.

• the same as energy.

• measured in Watts

• a product of voltage and current.

If a lamp is rated 100W, 120V then it consumes ____ Joules in 1 minute.

Select the equations that result from combining Ohm's and Watt's Law,

•  $P\ =\ V\times I$  

•  $V\ =\ I\times R$  

•  $P\ =\ \frac{V^2}{R}$  

•  $P\ =\ I^2\ \times R$  

Energy consumed by home appliances are conveniently measured in

• Watt meters.

• Kilowatts.

• Joules.

• Kilowatt-hours.

A consumer's kilowatt-hour meter displays 10456 at the start of a billing period and 10966 at the end of the period. How much kW hrs are consumed in that period?

• 21422

• 10456

• 510

• 10966