Question

A step-down transformer has 7500 turns on its primary coil, and 125 turns on its secondary coil. The voltage across the primary is 7200 V.a. What is the voltage across the secondary? Answerb. The current in the secondary is 36 A. What current flows in the primary? Answer

Answer 1

Given

Number of turns in primary coil, n=7500

Number of turns in secondary coil, n'=125

The voltage across the primary coil, V=7200 V

To find

a. What is the voltage across the secondary? Answer

b. The current in the secondary is 36 A. What current flows in the primary?

Step-by-step explanation

a.

Voltage across secondary coil is

`\begin{gathered} V^(\prime)=\frac{n^(\prime)}{n^\text{ }}V \\ \text{ }\Rightarrow V^(\prime)=(125)/(7500)*\text{ }7200 \\ \text{ }\Rightarrow V^(\prime)=120\text{ }V \end{gathered}`

b. The current in the secondary coil is I'=36A

We know,

`\begin{gathered} VI=V^(\prime)I^(\prime) \\ \Rightarrow7200I=120*36 \\ \Rightarrow I=0.60\text{ A} \end{gathered}`

Conclusion

a. The voltage across the secondary coil is 120 V

b. The current across the primary coil is 0.60 A