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NEET-XII-Physics

39: Alternating Current

with Solutions - page 3
Qstn# iii-7 Prvs-QstnNext-Qstn
  • #7
    An AC source rated 100 V (rms) supplies a current of 10 A (rms) to a circuit. The average power delivered by the source
    (a) must be 1000 W
    (b) may be 1000 W
    (c) may be greater than 1000 W
    (d) may be less than 1000 W
    digAnsr:   b,d
    Ans : (b) may be 1000 W
    (d) may be less than 1000 W
    The average power delivered by an AC source is given by,
    `` {P}_{avg}={V}_{rms}{I}_{rms}\,\mathrm{\,cos\,}\varphi ``
    Given:
    Vrms = 100 V
    Irms = 10 A
    `` \Rightarrow {P}_{avg}=1000\,\mathrm{\,cos\,}\varphi ``
    `` \because \varphi \in \left(-\frac{\,\mathrm{\,\pi \,}}{2},\frac{\,\mathrm{\,\pi \,}}{2}\right)``
    `` \Rightarrow \,\mathrm{\,cos\,}\varphi \in \left(0,1\right)``
    `` \therefore 0\le {P}_{avg}\le 1000``
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