A transformer is used to operate a model train. The transformer, which is plugge

Question

A transformer is used to operate a model train. The transformer, which is plugged into a standard electrical outlet, produces an output voltage of 17.1 V (rms), applied to the train's tracks. (The voltage supplied to transformer from outlet is 120 V.)

(a) What is the ratio of the number of turns in the primary to the number of turns in the secondary?

= 1

(b) If the train uses an average power of 12.1 W, what are the rms currents in the secondary and in the primary? Assume an ideal transformer, with no energy loss.

Iprimary

Isecondary

Explanation / Answer

part a ) Es/Ep = Ns/Np

Es = 17.1 V

Ep = 120 volt (rms)

Np/Ns = 120/17.1

Np/Ns = 7.0175 = 7 turn

if 120 is peak voltage then Eprms = 120/sqrt(2)

then Np/Ns = 120/sqrt(2)*17.1 = 4.96 = turn = 5 turn

part b )

P =VI

Iprimary = P/Vp

Vp = 120 (Assume it rms value )

Iprimary = 12.1/120 = 0.1008 Amp

if 120 is peak then Vprma = 120/sqrt(2)

Iprimary = 12.1 *sqrt(2)/120

Iprimary = 0.1425 Amp

Isecondary = P/Vs

Isecondary = 12.1/17.1 = 0.7076 Amp

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.