Q177 / 180 · KCET 2014 · Physics

A step down transformer has \( 50 \) turns on secondary and \( 1000 \) turns on primary winding. If a
transformer is connected to \( 220 \mathrm{~V} 1 \mathrm{AA} \).C. source, what is output current of the transformer?

  • A
    \( \frac{1}{20} A \)
  • Correct answer
    B
    \( 20 \mathrm{~A} \)
  • C
    \( 100 \mathrm{~A} \)
  • D
    \( 2 \mathrm{~A} \)

Solution

Given, number of turns on secondary, $N_{s}=50 ;$ number of turns on primary, $N_{P}=1000 ;$ source voltage $=220 \mathrm{~V} ;$ current $=1 \mathrm{~A}$. We know $\frac{N_{s}}{N_{p}}=\frac{V_{s}}{V_{p}}=\frac{I_{p}}{I_{s}}$ Therefore $\frac{N_{s}}{N_{p}}=\frac{I_{p}}{I_{s}} \Rightarrow I_{s}=\frac{N_{p}}{N_{s}} I_{p}$ Substituting the values, we get $I_{s}=\frac{1000}{50} \times 1=20 \mathrm{~A}$ Thus, output current of transformer $=20 \mathrm{~A}$

Hence, the correct answer is option: 'B'.

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