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 $200 V$, 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) $50: 1$
Show Answer
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 $\quad V _s=40000 V$
In step down transformer,
$$ \frac{N _p}{N _s}=\frac{V _p}{V _s}=\frac{40000}{200}=\frac{200}{1} $$
