Question

A transformer has 25 turns in the primary coil and 200 turns in the secondary coil. If 24 V is connected to the primary coil and a 20-Ω device is connected to the secondary coil, calculate the current in Amperes passing through the device.

Answer 1

There is a relation between current, voltage and number of turns in a transformer

$Constant=\frac{V_1}{V_2}=\frac{n_1}{n_2}=\frac{I_2}{I1}$

We have the number of turns for both coils and the voltage on the primary. with this we can get the voltage on the second coil

$\begin{gathered} \frac{24V}{V_2}=\frac{25}{200} \\ \\ V_2=192V \end{gathered}$

With this voltage we can get the current by using the next formula:

$\begin{gathered} V=IR \\ \\ 192V=I\cdot20\Omega \\ I=9.6A \end{gathered}$

Answer: I=9.6A