Question

The 400-turn primary coil of a step-down transformer is connected to an ac line that is 120 V rms. The secondary coil voltage is 6.50 V rms. Calculate the number of turns in the secondary coil.

Answer 1

Explanation:

The given data is as follows.

             $V_{1}$ = 120 V,    $V_{2}$ = 6.50 V

             $N_{1}$ = 400,     $N_{2}$ = ?

Formula to calculate the number of turns in secondary coil are as follows.

          $\frac{N_{1}}{N_{2}} = \frac{V_{1}}{V_{2}}$

Putting the given values into the above formula as follows.

         $\frac{N_{1}}{N_{2}} = \frac{V_{1}}{V_{2}}$

        $\frac{400}{N_{2}} = \frac{120}{6.50}$

              $N_{2}$ = 21.66

                          = 22 (approx)

Thus, we can conclude that number of turns in the secondary coil are 22.