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The correct option is (a) 28.125

The EXPLANATION is: For a QUARTER line WAVE, the characteristic impedance is the geometric mean of input and load impedances. Thus Zo^2 = Zin ZL. On SUBSTITUTING for Zo = 75 and Zin = 200,we get ZL = Zo^2/Zin = 75^2/200 = 28.125 ohm.

Right ANSWER is (a) Zo^2 = Zin ZL

The best I can EXPLAIN: The QUARTER wave transformer represents L = λ/4. In this case, the characteristic impedance is the geometric mean of the input and load impedances. THUS Zo^2 = Zin ZL is the required condition.

Correct OPTION is (B) L = λ/8

Best EXPLANATION: Maximum TRANSMISSION of power will occur, when the transmission line is matched. This implies that the input and CHARACTERISTIC impedances are the same. This condition is possible for l = λ/8 and l = ∞. Since l = ∞ is not feasible, the best option is l = λ/8.

Correct option is (d) Zin = ZL

Explanation: When the transmission LINE has a length same as that of the WAVELENGTH of the wave propagating through it, the INPUT IMPEDANCE will be same as the LOAD impedance. This is the case where the wave is not amplified. The transmission line acts as a buffer.

Right option is (d) 50

Explanation: From the transmission line EQUATION, the infinite line will have an INPUT impedance same as that of the characteristic impedance. Thus Zin = Zo for L->∞. This SHOWS that the line will be MATCHED. The input impedance for the given case is 50 ohm.

The correct answer is (a) R

To elaborate: The transmission line EQUATION consists of secondary parameters only, which are DERIVED from the primary parameters. The PROPAGATION constant, load impedance and the CHARACTERISTIC impedance are related in the transmission line equation.

Right answer is (C) 2 + 3j

The EXPLANATION: The propagation CONSTANT is GIVEN by γ = α + jβ. Given that α = 2 and β = 3. Thus we get the propagation constant as γ = 2 + 3j.

Correct ANSWER is (B) False

For EXPLANATION: There are always some distortions, even in the perfect transmission LINE. This is due to the variation of the secondary parameters. The attenuation constant causes the frequency distortion, whereas the phase constant causes the phase distortion.

The correct CHOICE is (C) Neper

Easy EXPLANATION: Attenuation CONSTANT is the MEASURE of the power loss of the wave during its transmission. It is expressed in terms of neper and 1 neper= 8.686 decibel/m.

Right ANSWER is (a) Product of attenuation constant and length

Easy explanation: The ELECTRICAL length in a transmission LINE refers to the product of the attenuation constant α and the length of the line l. It is GIVEN by αl.

Right choice is (a) V = ω/β

For EXPLANATION I WOULD say: The velocity of a wave is the RATIO of the frequency in radian/second to the phase CONSTANT. It is GIVEN by V = ω/β.

Right option is (b) 3.14

Easiest explanation: The phase constant is GIVEN by β = 2π/λ. On substituting for λ = 2, we GET β = 2π/2 = 3.14 UNITS.

Right OPTION is (B) 0.133 GHz

Explanation: The frequency and wavelength relation is given by F = V/λ. On SUBSTITUTING for v and λ, we get f = 4 x 10^8/3 = 0.133 GHz.

Correct OPTION is (d) 0.05

For explanation: The wavelength is given by the ratio of the velocity to the frequency of the WAVE. In air medium, the velocity can be assumed as the speed of light. On SUBSTITUTING for v and F, we get λ = v/f = 3×10^8/6×10^9 = 0.05 units.

The correct answer is (B) 1

Easy explanation: The wavelength and the phase CONSTANT are RELATED by λ = 2π/β, where β is given as 6.28. On substituting for β, we get λ = 2π/6.28 = 1 unit.

Right choice is (c) Zo = √(L/C)

The explanation is: The CHARACTERISTIC impedance is given by the square root of the RATIO of the inductance to the capacitance. Thus Zo = √(L/C) is the required EXPRESSION.

Correct option is (c) 12

Best explanation: The propagation constant is GIVEN by γ = √(ZY), where Z is given by 9 and Y is 16. On substituting the given values, the propagation constant will be γ = √(ZY) = √(9 x 16) = 12 units.

Correct option is (d) 20

Easy EXPLANATION: By Ohm’s law, the IMPEDANCE is the ratio of the voltage to the CURRENT. On substituting for V = 24 and I = 1.2, we get Z = V/I = 24/1.2 = 20 units.

Right choice is (c) C

Easiest explanation: Conductors separated by insulating DIELECTRICS in ORDER to STORE electric charges, GIVES rise to the capacitance effect. The capacitance is DISTRIBUTED in the whole conductor length.

The correct OPTION is (b) L

The explanation: When the CONDUCTORS carry current, the CONDUCTOR will be surrounded and linked by magnetic flux. The flux LINKAGES per ampere of current gives rise to the effect of inductance. It is denoted by L.

Correct choice is (d) R

Easiest explanation: The resistance is a primary parameter that is UNIFORMLY distributed along the LENGTH of the CONDUCTOR. It depends on the CROSS section area and the length of the conductor.

Correct answer is (b) Distributed

To ELABORATE: In distributed lines, the PRIMARY parameters are distributed along the circuit with each ELEMENTAL length having its own values and the concentration of the individual parameters is not possible. An EXAMPLE is the transmission of power.

The correct answer is (a) LUMPED

The best explanation: The networks in which the R, L, C PARAMETERS are individually concentrated or lumped at discrete points in the circuit are called lumped networks. These networks can be identified definitely as representing a particular PARAMETER. An example is the filters.

Right option is (b) ATTENUATION CONSTANT

The BEST explanation: The PRIMARY parameters of a transmission line are the resistance, inductance, capacitance and CONDUCTANCE. The attenuation, phase and propagation constant are secondary parameters. Thus the odd one out is the attenuation constant.