The resistance of the primary coil of 1:10 step-down transformer is 1Ω. With the secondary circuit open, the primary is connected to a 12 V AC generator. The primary current is:
Correct answer: A. Essentially zero
- A. Essentially zero
- B. About 12 A
- C. About 120 A
- D. Depends on the actual number of turns in the primary coil
Explanation
The explanation is: Vsls = 0 So, the input power must be zero or very small. Thus, a very small current (Ip) flows in the primary coil.
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About Electromagnetic Induction
Changing magnetic flux induces an emf according to Faraday's law, while Lenz's law gives the direction that opposes the change producing it. Transformers apply induction between coils to step alternating voltage up or down, with turns ratio, current transformation and energy losses determining practical operation.
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