Question

A neon sign that requires a voltage of 11,000 v is plugged into a 120-v wall outlet. what turns ratio (secondary/primary) must a transformer have to power the sign?

Answer 1

The equation that relates the voltages and the number of turns in a transformer is
$\frac{V_s}{V_p}= \frac{N_s}{N_p}$
where $V_s = 120 V$ is the voltage in the secondary coil, $V_p=11000 V$ is the voltage in the primary coil, and $N_s$ and $N_p$ are the number of turns on the secondary and primary coils.

Using the numbers, we find the ratio between the number of turns:
$\frac{N_s}{N_p}= \frac{V_s}{V_p}= \frac{120 V}{11000 V}=0.0109$