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A step down transformer works on 220 V a mains. What is the efficiency of the transformer when a bulb of 100 W, 20 V is connected to the a mains and the current in the primary is 0.5 A ? |
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Answer» Data: Vp = 220V, Vs = 20V, Ps = 100W, Ip = 0.5 A The Input power. Pp = IpVp = (0.5)220) = 110 W The output power, Ps = 100 W ∴ The efficiency of the transformer = \(\cfrac{output \,power}{input \,power}\) = \(\cfrac{100}{110}\) = 0.9091 or 90.91% |
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