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Electric circuits miscellaneous

  1. For the circuit shown in the given figure, if input impedance Z1 at port 1 is given by
    Z1 = K1
    (s + 2)
    s + 5

    then input impedance Z2 at port 2 will be

    1. K2(s + 3)
      s + 5

    2. K2(s + 2)
      s + 3

    3. K2 s
      s + 5

    4. K2 s
      s + 2

Correct Option: C

Z1 = K1
(s + 2)
s + 5

∴ Z1 = R1
(R2 + Ls)
R1 + R2 + Ls

= R1L
R2
L + (s)
L
R1 + R2
L + (s)

= R1
R2
L + (s)
R1 + R2
L + (s)

∴ R1 = K1
R2
= 2 ,
R1 + R2
= 5
LL

Again , R2 =
2
K1 , L =
K
33

∴ Z2 =
Ls(R1 + R2)
Ls + R2Cs

=
K1
K1 + 2
3s3K1
K1
sK1 +
2
33K1

= s
5
3K1 =
K2s
(s + 5)(s + 5)

∴ K2 =
5
K1
3



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