The given transformer ratio is 200/1000 V and the emf per turn is 10 V. For the 200 V winding, N = E/(emf per turn) = 200/10 = 20 turns.
Formula / Key Relation
Emf per turn = E/N
N = E / (emf per turn)
N1 = 200/10 = 20 turns
Detailed Explanation
Concept & ReasoningTransformer induced emf is proportional to the number of turns. If emf per turn is already supplied, the turn count follows directly by dividing the winding voltage by emf per turn. The wording asks for the primary turns in a 200/1000 V transformer; taking the first rating as the primary winding gives E1 = 200 V. Thus N1 = 20. No turns-ratio calculation is required beyond identifying the correct winding voltage.How to Solve It in the ExamWhen volts/turn is given, simply divide the winding voltage by volts/turn.Important Exam PointCheck which voltage belongs to the winding named in the…
Concept & Reasoning
Transformer induced emf is proportional to the number of turns. If emf per turn is already supplied, the turn count follows directly by dividing the winding voltage by emf per turn. The wording asks for the primary turns in a 200/1000 V transformer; taking the first rating as the primary winding gives E1 = 200 V. Thus N1 = 20. No turns-ratio calculation is required beyond identifying the correct winding voltage.
How to Solve It in the Exam
When volts/turn is given, simply divide the winding voltage by volts/turn.
Important Exam Point
Check which voltage belongs to the winding named in the question before calculating.
Related Revision Path
This question sits in the revision path Electrical Machines → Transformers → EMF Equation .
Quick Trick
When volts/turn is given, simply divide the winding voltage by volts/turn.
Common Mistake
Using 1000 V instead of the 200 V primary rating would give 100 turns, which is not among the stated options.
Exam Tip
Check which voltage belongs to the winding named in the question before calculating.
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