Question

A model electric train requires 12 V to operate. When connected to a household voltage of 120 V, a transformer is needed. If the primary coil has 250 turns, how many turns must the secondary coil have?

Answer 1

We are given that a transformer is needed to convert 120V into 12V. To determine the number of turns in the secon dary coil we will use the following formula:

$\frac{V_2}{V_1}=\frac{N_2}{N_1}$

Where:

$\begin{gathered} V_2=\text{ secondary voltage} \\ V_1=\text{ primary voltage} \\ N_1=\text{ number of turns on primary} \\ N_2=\text{ number of turns on secondary} \end{gathered}$

Now, we plug in the values:

$\frac{12V}{120V}=\frac{N_2}{250}$

Now, we multiply both sides