Question

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 transformers is $1:10.$ If the power to the consumers has to be supplied at $200V,$ the ratio of the number of turns in primary to that in the secondary in the step-down transformer is

• A. $200:1$
• B. $150:1$
• C. $100:1$
• D. $50:1$

Answer 1

The correct option is A $200:1$

For step up

$\frac{4000}{x}=\frac{1}{10}-\left(i\right)$

For step down

$\frac{x}{200}=N-\left(ii\right)$

$x=$ step up voltage

Multiplying $\left(i\right)$ and $\left(ii\right)$

$\frac{4000}{x}\times \frac{x}{200}=\frac{1}{10}\times NN=200$

Ratio$=200:1$.