Calculate the rate at which energy is transferred by 220 V mains supply which provides a current of 0.1 A to a LED?
Correct answer: B. 22 W
- A. 22 kW
- B. 22 W
- C. 2.2 kW
- D. 2.2 W
Explanation
The rate of energy transfer is power (P). The formula for electrical power is P = VI. P = (220 V) × (0.1 A) = 22 W.
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About Current Electricity
Steady current relates charge flow to potential difference, resistance and resistivity, including how temperature changes a conductor's resistance. Sources with internal resistance have terminal voltage below their emf when delivering current, and maximum power output occurs under a specific load condition rather than at zero resistance.
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