If a transformer has a primary coil with 115 volts and 330 turns, how many turns are needed in the secondary coil to produce 28 volts?

To determine the number of turns needed in the secondary coil of a transformer to produce a specific voltage, you can use the transformer turns ratio formula. This formula relates the voltage and the number of turns in the primary and secondary coils:

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

]

Where:

• (V_p) is the primary voltage (115 volts in this case),
• (V_s) is the secondary voltage (28 volts),
• (N_p) is the number of turns in the primary coil (330 turns),
• (N_s) is the number of turns in the secondary coil (the unknown we need to find).

Using the values provided, you can rearrange the formula to solve for (N_s):

[ N_s = N_p \times \frac{V_s}{V_p} ]

Substituting in the known values:

[ N_s = 330 \times \frac{28}{115} ]

Calculating the fraction:

[ \frac{28}{115} \approx 0.2435 ]

Then multiply:

[ N_s = 330 \times 0.2435