Transformation 26951

The bell uses 8 V alternating voltage obtained from the 220 V mains. The secondary coil of the bell transformer has 60 turns. How many turns must the primary coil have? What is the transformation ratio?

Correct answer:

n₁ =  1650
k =  0.0364

Step-by-step explanation:

$$\begin{gathered} u_2=8\text{V} \\ {u}_1=220\text{V} \\ {n}_2=60\text{V} \\ k=\frac{u_2}{u_1}=\frac{n_2}{n_1} \\ k=\frac{u_2}{u_1}=\frac{8}{220}=\frac{2}{55}\doteq 0.0364 \\ {n}_1=n_2/k=60/\frac{2}{55}=60:\frac{2}{55}=60\cdot \frac{55}{2}=\frac{60\cdot 55}{2}=\frac{3300}{2}=1650 \end{gathered}$$

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