Question

A transformer $\mathrm{r}=12$ is connected to $220\mathrm{V}$ a.c. supply. What is its output potential?

Answer 1

Step-1 Given data

The primary or input potential ${\mathrm{E}}_{\mathrm{p}}=220volts$

And $r=12$

Where $\mathrm{r}$ is the ratio of number of turns in secondary coil $\left({\mathrm{N}}_{\mathrm{s}}\right)$ to number of turns in primary coil $\left({\mathrm{N}}_{\mathrm{p}}\right)$

i.e. $\mathrm{r}=\frac{{\mathrm{N}}_{\mathrm{s}}}{{\mathrm{N}}_{\mathrm{p}}}$

Step-2 Finding output potential

By using the relation

$\frac{{\mathrm{E}}_{\mathrm{s}}}{{\mathrm{E}}_{\mathrm{p}}}=\frac{{\mathrm{N}}_{\mathrm{s}}}{{\mathrm{N}}_{\mathrm{p}}}$

Where

$$\begin{gathered} E_s=secondarypotentialoroutputpotential \\ {E}_p=primarypotentialorinputpotential \\ {N}_s=Numberofturnsinsecondarycoil \\ {N}_p=Numberofturnsinprimarycoil \end{gathered}$$

Now,

$$\begin{gathered} \frac{E_s}{220}=\frac{N_s}{N_p}=r \\ \frac{E_s}{220}=12 \\ {E}_s=12\times 220 \\ {E}_s=2640volts \end{gathered}$$

Hence, output potential is $2640\mathrm{volts}.$