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Question : 22
Total: 36
(a) Write two points of difference between electric energy and electric power.
(b) Out of60 W and 40 W lamps, which one has a higher electrical resistance when in use.
(c) What is commercial unit of electric energy ? Convert it into Joules.
(b) Out of
(c) What is commercial unit of electric energy ? Convert it into Joules.
Solution:
(a)
(b) Power ( P ) =
i.e., At same voltage, power( P ) is inversely proportional to resistance (R).
∴ 40 W lamp has higher resistance.
(c) The commercial unit of electrical energy is kWh.
1 kWh = 1000 W × 1 hr
= 1000 W × 3600 s
= 36 × 10 5 Ws
= 3.6 × 10 6 J .
S.No | Electric energy | Electric power |
---|---|---|
1 | Electrical energy consumed by an electrical appliance is given by the product of its power rating and time for which it is used. | It is the rate at which electrical energy is consumed. |
2 | It is measured in kWh | It is measured in watt or kilowatt. |
i.e., At same voltage, power
(c) The commercial unit of electrical energy is kWh.
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