Network theory miscellaneous

Network theory miscellaneous

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Network Theory

Network Elements and the Concept of Circuit
Network theory miscellaneous
  1. Two AC sources feed a common variable resistive load as shown in figure. Under the maximum power transfer condition, the power absorbed by the load resistance RL is—










  1. View Hint View Answer Discuss in Forum

    The given circuit:

    Zth = (6 + j8) || (6 + j8)
    = (6 + j8)/2 = (3 + j4) Ω
    Equivalent circuit for Vth:

    Applying KCL

    Vth – 110   0°
    		 +
    Vth – 90   0°
    		 = 0
    6 + j86 + j8

    or
    Vth =
    200   0°
    		 = 100   0°
    2

    Now, for maximum power transfer theorem,
    ZL = Z*th
    or
    Rth = RL
    and power absorbed by RL
    Pmax =
    V2th
    4RL

    or
    Pmax =
    (100)2
    4 × 5

    or
    Pmax = 500W
    where RL = R2s + X2s
    or
    RL = 32 + 42 (since RL = 3 + j4)
    or
    RL = 5Ω
    Hence alternative (C) is the correct choice.

    Correct Option: C

    The given circuit:

    Zth = (6 + j8) || (6 + j8)
    = (6 + j8)/2 = (3 + j4) Ω
    Equivalent circuit for Vth:

    Applying KCL

    Vth – 110   0°
    		 +
    Vth – 90   0°
    		 = 0
    6 + j86 + j8

    or
    Vth =
    200   0°
    		 = 100   0°
    2

    Now, for maximum power transfer theorem,
    ZL = Z*th
    or
    Rth = RL
    and power absorbed by RL
    Pmax =
    V2th
    4RL

    or
    Pmax =
    (100)2
    4 × 5

    or
    Pmax = 500W
    where RL = R2s + X2s
    or
    RL = 32 + 42 (since RL = 3 + j4)
    or
    RL = 5Ω
    Hence alternative (C) is the correct choice.