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Question
Given the input current 15 A and the input voltage of 100 V for a step-up transformer having 90% efficiency, find the output power and the voltage in the secondary if the output current is 3 A.
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Solution
\[\text { Input current } = 15 A\]
\[\text { Input voltage } = 100 V\]
\[efficiency = 90 % = 90/100\]
\[\frac{\text { Output power }}{\text { Input power}} = 0 . 9\]
\[\frac{\text { Output power }}{\text { Input voltage} \text { times Input current }} = \frac{\text { Output power}}{15 \times 100} = 0 . 9\]
\[\text { Output power} = 15 \times 100 \times 0 . 9 = 1350 W\]
\[\text { Outpur current} = 3 A\]
\[\text { Output voltage } = \frac{\text { Output power}}{\text { Output current}} = \frac{1350}{3} = 450 V\]
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