Chapter 7, Problem 48R

To determine

To calculate: the number of turns in the secondary coil of the step-down transformer.

Answer to Problem 48R

The number of turns in the secondary coil of the step-down transformer is $\underset{\_}{25}$ .

Explanation of Solution

Given data:

Input voltage, $V_{in}=2400\text{ V}$

Output voltage, $V_{out}=120\text{ V}$

Number of turns in the primary coil, $N_1=500$

Formula used:

Transformer Voltage Equation:

  $\frac{V_{out}}{V_{in}}=\frac{N_2}{N_1}$

Where $V_{out}$ is the output voltage of the transformer in volts, $V_{in}$ is its input voltage in volts, $N_2$ is the turns in secondary coil, and $N_1$ is the turns in primary coil.

Calculation:

As per the problem,

  $\begin{array}{l}{V}_{in}=2400\text{ V}\\ V_{out}=120\text{ V}\\ N_1=500\end{array}$

Substitute the values of input, output voltage and the number of turns in the primary coil, in the rearranged transformer voltage equation to get the turns in secondary coil:

  $\begin{array}{l}\frac{V_{out}}{V_{in}}=\frac{N_2}{N_1}\\ N_2=\frac{V_{out}}{V_{in}}\times N_1\\ N_2=\frac{120}{2400}\times 500\\ N_2=25\end{array}$

Conclusion:

The number of turns in the secondary coil of the step-down transformer is $\underset{\_}{25}$ .