Physics · Grades 10–12
Ideal transformer voltage ratio
This ideal transformer model uses alternating voltage; it is not a mains-wiring activity.
Rule and assumptions
This ideal transformer model uses alternating voltage; it is not a mains-wiring activity.
Vs/Vp = Ns/Np
Worked examples
An ideal AC transformer has primary 700 turns, secondary 2700 turns and primary voltage 14 V. Find secondary voltage. Paper model only. Round to 3 decimal places if needed. Answer in V.
Vs/Vp = Ns/Np 14 × 2700 / 700 = 54
54 V
An ideal AC transformer has primary 1600 turns, secondary 2300 turns and primary voltage 43 V. Find secondary voltage. Paper model only. Round to 3 decimal places if needed. Answer in V.
Vs/Vp = Ns/Np 43 × 2300 / 1600 = 61.813
61.813 V
Try two questions
An ideal AC transformer has primary 300 turns, secondary 900 turns and primary voltage 21 V. Find secondary voltage. Paper model only. Round to 3 decimal places if needed. Answer in V.
An ideal AC transformer has primary 100 turns, secondary 400 turns and primary voltage 5 V. Find secondary voltage. Paper model only. Round to 3 decimal places if needed. Answer in V.
Answers and reasoning
Answers and marking notes
- 63 V
Vs/Vp = Ns/Np 21 × 900 / 300 = 63
- 20 V
Vs/Vp = Ns/Np 5 × 400 / 100 = 20
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · independent educational and translation review required. Suggested grades are not official curriculum alignment.