Engineering Board Exam Reviewer · Alternating Current and Voltage · medium
Two sinusoids of the same frequency are plotted below: a voltage v (solid) and a current i (dashed). Use the time axis (milliseconds, one cycle =12 ms) to decide how i is related to v.
- i lags v by 30°
- i leads v by 30°
- i leads v by 60°
- i lags v by 60°
Answer
B. i leads v by 30°
Solution
i reaches its positive peak earlier than v does, by t=1 ms. =360°· t/T=360°· 1 ms12 ms=30°. Since i peaks earlier than, it leads v.
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