Electromagnetic Induction and Alternating Current 7 Question 18
####18. In the method using the transformers, assume that the ratio of the number of turns in the primary to that in the secondary in the step-up transformer is $1: 10$. If the power to the consumers has to be supplied at $200 \mathrm{~V}$, the ratio of the number of turns in the primary to that in the secondary in the step-down transformer is
(a) $200: 1$
(b) $150: 1$
(c) $100: 1$
(d) $50: 1$
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Answer:
Correct Answer: 18. (a)
Solution:
- During step-up, $\frac{N_{p}}{N_{s}}=\frac{V_{p}}{V_{s}}$ or $\frac{1}{10}=\frac{4000}{V_{s}}$
or $\quad V_{s}=40000 \mathrm{~V}$
In step down transformer,
$$ \frac{N_{p}}{N_{s}}=\frac{V_{p}}{V_{s}}=\frac{40000}{200}=\frac{200}{1} $$
