Chapter 37, Problem 53A

A model electric train requires 6 V to operate. When connected to a 120-V house-hold circuit, a transformer is needed. If the primary coil of the transformer has 240 windings, show that there should be 12 turns in the secondary coil.

To determine

To show: there are $12turns$ in the secondary coil

Answer to Problem 53A

The number of turns on secondary coil is $12turns$

Explanation of Solution

Given:

Voltage in the train $\left(V_2\right)=6V$

House -hold circuit voltage $\left(V_1\right)=120V$

Number of turns on primary coil $\left(N_1\right)=240$

Number of turns on secondary coil $\left(N_2\right)=12$

Formula used:

  $\frac{V_1}{V_2}=\frac{N_1}{N_2}$ .

Calculation:

The relation between voltage and number on turns on primary and secondary winding is,

  $\frac{V_1}{V_2}=\frac{N_1}{N_2}$

The equation becomes

  $\begin{array}{l}{N}_2=N_1\frac{V_2}{V_1}\\ N_2=240\times \frac{6}{120}\\ =12turns\end{array}$

The number of turns required on the secondary winding is $12turns$

Conclusion: 

The number of turns on the secondary winding is $12turns$