Question

A typical wall outlet voltage in the United States is 120 volts. Personal MP3 players require much smaller voltages, typically 335.7 mV. If the number of turns in the primary coil is 3575, calculate the number of turns on the secondary coil of the adapter transformer. number of turns: _________turns

Answer 1

10 turns

Step-by-step explanation:

Parameters given:

Input voltage,
`V_(in)` (voltage at the primary coil) = 120 V

Output voltage,
`V_(out)` (voltage at the secondary coil) = 335.7 mV = 0.3357 V

Number of turns in primary coil,
`N_p` = 3575

The ratio relating the turns in the primary and secondary coil in of a transformer and the number of turns in each coil is given as:

`(V_(out))/(V_(in)) = (N_s)/(N_p)`

where
`N_s` = Number of turns in secondary coil

Therefore:

`N_s = (N_p * V_(out))/(V_(in))`

`N_s = (3575 * 0.3357)/(120)`

`N_s = 10.001` ≅ 10 turns

There are 10 turns in the secondary coil of the adapter.

Answer 2

10 turns

Step-by-step explanation:

From Transformer equation,

Ns/Np = Vs/Vp................... Equation 1

Where Np = Number of turns in the secondary coil, Np = Number of turns in the primary coil, Vs = Voltage in the secondary coil, Vp = Voltage in the primary coil.

make Ns the subject of the equation

Ns = (Vs/Vp)Np.................. Equation 2

Given: Vs = 335.7 mV = 0.3357 V, Vp = 120 V, Np = 3575

Substitute into equation 2

Ns = (0.3357/120)3575

Ns = 10 turns

Ns = 10 turns

Thus the number of turns in the secondary coil = 10 turns