NEET 2019 Odisha · PhysicsAC generatorPrevious Year Question
The variation of EMF with time for four types of generators are shown in the figures. Which amongst them can be called AC?
Answer: (B) , (b), (c) and (d). Answer: (b) Solution: An emf is "alternating" (AC) if it is periodic and reverses polarity (changes sign) over each cycle — its exact waveform shape (sinusoidal, triangular, sawtooth, square) does not matter.
- A.and (d)
- B., (b), (c) and (d)✓
- C.and (b)
- D.only (a)
Correct Answer
(B) , (b), (c) and (d)
Solution & Explanation
Answer: (b) Solution: An emf is "alternating" (AC) if it is periodic and reverses polarity (changes sign) over each cycle — its exact waveform shape (sinusoidal, triangular, sawtooth, square) does not matter. All four graphs (a)–(d) cross the time axis and reverse sign periodically, so all four represent AC. Hence (a), (b), (c) and (d) → answer B.
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