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A power transmission line feeds input power at 2400 V to a step-down transformer which delivers power at 240 V with its primary windings having 5000 turns. If the current in the primary coil of the transformer is 5 A and its efficiency is 80 % , then what is the output current (in A )?

Correct answer

40

Step-by-step solution

ε p = 2400   V ,   N p = 5000 ε s = 240   V ,   I p = 5   A η = 80 % = 0 . 8 η = P out P in = ε s I s ε p I p ⇒ I s = η ε p I p ε s = 0 . 8 × 2400 × 5 240 = 40   A

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