Question

In a step up transformer the turn ratio is 1 : 10. A resistance of $200\,\Omega$ connected across the secondary is drawing a current of 0.5 A. What is the primary voltage and current?

• A. 50 V, 1 A
• B. 10 V, 5 A
• C. 25 V, 4 A
• D. 20 V, 2 A

Answer 1

Answer: (B)

10 V, 5 A

Answer 2

Given, ${{N}_{p}}:{{N}_{s}}=1:10$ ${{V}_{s}}={{I}_{s}}\times R$ $=0.5\times 200=100\,\,volt$ ${{V}_{p}}=?,{{I}_{p}}=?$ Transformation ratio $k=\frac{{{N}_{s}}}{{{N}_{p}}}=\frac{{{V}_{s}}}{{{V}_{p}}}=\frac{{{I}_{p}}}{{{I}_{s}}}$ $\therefore$ $\frac{10}{1}=\frac{100}{{{V}_{p}}}$ ${{V}_{p}}=10\,\,volt$ Again, $\frac{10}{1}=\frac{{{I}_{p}}}{0.5}$ ${{I}_{p}}=5\,\,A$