Question

If a step-down transformer has an input voltage of 150 V and 1000 coils in the primary, what is the output voltage if there are 800 coils in the secondary? A) 500 vB) 135 vC) 188 v D) 120 v

Answer 1

ANSWER

$D)\text{ }120\text{ }V$

EXPLANATION

To find the output voltage, we have to apply the transformer equation:

$\frac{V_p}{V_s}=\frac{N_p}{N_s}$

where Vp = primary voltage = 150 V

Vs = secondary voltage

Np = number of turns in the primary coil = 1000

Ns = number of turns in the secondary coil = 800

Therefore, solving for Vs in the equation above, the output voltage (secondary voltage) is:

$\begin{gathered} \frac{150}{V_s}=\frac{1000}{800} \\ \\ V_s=\frac{150*800}{1000} \\ \\ V_s=120\text{ }V \end{gathered}$

The correct answer is option D.