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 transformer is $1:10.$ If the power to the consumers has to be supplied at $200V,$ 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. $50:1$
• C. $150:1$
• D. $100:1$

Answer 1

The correct option is A $200:1$

$\frac{V_s}{V_p}=\frac{N_s}{N_P}$
$\Rightarrow \frac{V_s}{4000}=\frac{10}{1}\Rightarrow V_s=40,000\text{volt}$
$\frac{N_s}{N_P}=\frac{V_P}{V_s}$
$=\frac{40,000}{200}=200:1$