Question

A 20 Ohm resistance is connected

Answer 1

Answer: 225 V

Explanation:

Given:

Secondary voltage,V2 = 150v

Resistance is connected across secondary winding,∴R2 = 20Ω

Supply current, ie, I1 = 5A

$\text{Now, secondary current,} \ I_{2}=\frac{V_{2}}{R_{2}}=\frac{150}{20}=7.5 \therefore I_{2}=7.5 \mathrm{~A} For Transformers, we have \frac{N_{2}}{N_{1}}=\frac{V_{2}}{V_{1}}=\frac{I_{1}}{I_{2}} so, Taking \frac{N_{2}}{N_{1}}=\frac{l_{1}}{l_{2}} inserting all given \& obtained values, we get \frac{N_{2}}{N_{1}}=\frac{5}{7.5} \therefore \text { Turns ratio }=\frac{N_{1}}{N_{2}}=\frac{7.5}{5}=\frac{3}{2}=3: 2$

$\text{Again taking,}\frac{N_{1}}{N_{2}}=\frac{V_{2}}{V_{1}} \\So, \\ V_{1}=\frac{N_{1}}{N_{2}} V_{2}\\ inserting all values, we get, V_{1}=\frac{7.5}{5} * 150=225 \\Therefore, \fbox{Primary voltage, { V_{1}=225 \mathrm{~V} }}$