This set of Network Theory Questions and Answers for Entrance exams focuses on “Classification of Pass Band and Stop Band”.
1. The relation between α, β, ϒ is?
a) α = ϒ + jβ
b) ϒ = α + jβ
c) β = ϒ + jα
d) α = β + jϒ
View Answer
Explanation: We know that the propagation constant is a complex function and the real part of the complex propagation constant is a measure of the change in magnitude of the current or voltage in the network known as attenuation constant and imaginary part is a measure of the difference in phase between the input and output currents or voltages known as phase shift constant. ϒ = α + jβ.
2. If Z1, Z2 are same type of reactance, then |Z1/4 Z2| is real, then the value of α is?
a) α = sinh-1√(Z1/4 Z2)
b) α = sinh-1√(Z1/Z2)
c) α = sinh-1√(4 Z1/Z2)
d) α = sinh-1√(Z1/2 Z2)
View Answer
Explanation: Z1, Z2 are same type of reactance and |Z1/4 Z2| is real. |Z1/4 Z2| > 0. The value of α is α = sinh-1√(Z1/4 Z2).
3. If Z1, Z2 are same type of reactance, then |Z1/4 Z2| is real, then?
a) |Z1/4 Z2| = 0
b) |Z1/4 Z2| < 0
c) |Z1/4 Z2| > 0
d) |Z1/4 Z2| >= 0
View Answer
Explanation: If Z1 and Z2 are same type of reactances, then √(Z1/4 Z2) should be always positive implies that |Z1/4 Z2| > 0.
4. Which of the following expression is true if Z1, Z2 are same type of reactance?
a) sinhα/2 sinβ/2=0
b) coshα/2 sinβ/2=0
c) coshα/2 cosβ/2=0
d) sinhα/2 cosβ/2=0
View Answer
Explanation: If Z1, Z2 are same type of reactance, then the real part of sinhϒ/2 = sinhα/2 cosβ/2 + jcoshα/2 sinβ/2 should be zero. So sinhα/2 cosβ/2=0.
5. Which of the following expression is true if Z1, Z2 are same type of reactance?
a) sinhα/2 cosβ/2=x
b) coshα/2 cosβ/2=0
c) coshα/2 sinβ/2=x
d) sinhα/2 sinβ/2=0
View Answer
Explanation: If Z1, Z2 are same type of reactance, then the imaginary part of sinhϒ/2 = sinhα/2 cosβ/2 + jcoshα/2 sinβ/2 should be some value. So coshα/2 sinβ/2=x.
6. The value of α if Z1, Z2 are same type of reactance?
a) 0
b) π/2
c) π
d) 2π
View Answer
Explanation: As sinhα/2 cosβ/2=0 and coshα/2 sinβ/2=x, the value of α if Z1, Z2 are same type of reactance is α = 0.
7. The value of β if Z1, Z2 are same type of reactance?
a) 2π
b) π
c) π/2
d) 0
View Answer
Explanation: The value of β if Z1, Z2 are same type of reactances, then sinhα/2 cosβ/2=0 and coshα/2 sinβ/2=x. So the value of β is β = π.
8. If Z1, Z2 are same type of reactance, and if α = 0, then the value of β is?
a) β=2 sin-1(√(Z1/4 Z2))
b) β=2 sin-1(√(4 Z1/Z2))
c) β=2 sin-1(√(4 Z1/Z2))
d) β=2 sin-1(√(Z1/Z2))
View Answer
Explanation: If α = 0, sin β/2 = x(√(Z1/4 Z2). But sine can have a maximum value of 1. Therefore the above solution is valid only for Z1/4 Z2, and having a maximum value of unity. It indicates the condition of pass band with zero attenuation and follows the condition as -1 < Z1/4 Z2 <= 0. So β=2 sin-1(√(Z1/4 Z2)).
9. If the value of β is π, and Z1, Z2 are same type of reactance, then the value of β is?
a) α=2 cosh-1√(Z1/2 Z2)
b) α=2 cosh-1√(Z1/Z2)
c) α=2 cosh-1√(4 Z1/Z2)
d) α=2 cosh-1√(Z1/4 Z2)
View Answer
Explanation: If the value of β is π, cos β/2 = 0. So sin β/2 = ±1; cosh α/2 = x = √(Z1/4 Z2). This solution is valid for negative Z1/4 Z2 and having magnitude greater than or equal to unity. -α <= Z1/2 Z2 <= -1. α=2 cosh-1√(Z1/4 Z2).
10. The relation between Zoπ, Z1, Z2, ZoT is?
a) ZoT = Z1Z2/Zoπ
b) Zoπ = Z1Z2/ZoT
c) ZoT = Z1Z1/Zoπ
d) ZoT = Z2Z2/Zoπ
View Answer
Explanation: The characteristic impedance of a symmetrical π-section can be expressed in terms of T. Zoπ = Z1Z2/ZoT.
Sanfoundry Global Education & Learning Series – Network Theory.
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