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In an A.C. circuit the current is 2 A, the voltage is 220 V and the power is 40 W. The power factor is .........

Asked in RS Academy GUJCET booklet · Power factor

• (1) 0.9
• (2) 0.09
• (3) 1.8
• (4) 0.18

Step-by-step solution

Why the other options are wrong

• (1) 0.9 is (40)/(44): the product VI=440 taken as 44, a decimal-place slip. The power factor is (40)/(440).
• (3) No single slip gives 1.8, and it is impossible on sight: a power factor is cos φ, which can never be more than 1.
• (4) 0.18=(40)/(220) divides the power by the voltage alone and forgets the current. The power factor is P/(VI).

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