electrical energy formula

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formulas

If the exam say if a bulb tranfers 7000 joules a minute work out its power

7000

--------

60           =116.6

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formula

when the exam asks how much electrical energy,in kwh,is tranferred when a 2 kw iron is use for 30 mins.

2kw

-------

2      =   1 kwh

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formula

a machine has an input power of 100kw and a useful power rating of 40 whats it efficency?

40

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100=0.4*100=40%

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