Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II NETWORK ANALYSIS AND TRANSMISSION LINES Previous Question Paper (September 2021 - R18)
Answer any five questions. All questions carry equal marks.
Main
Discuss the dot convention used in magnetically coupled coils.
Answer
The dot convention is a graphical method used to determine the polarity of the induced voltage in magnetically coupled coils without requiring knowledge of the physical winding direction. When current enters the dotted terminal of one coil, it produces a magnetic flux that adds to the flux produced by current entering the dotted terminal of the coupled coil. The convention follows two primary rules:
- If a time-varying current enters the dotted terminal of one coil, the reference polarity of the mutual voltage in the second coil is positive at its dotted terminal.
- If a current enters the undotted terminal of one coil, the reference polarity of the mutual voltage in the second coil is positive at its undotted terminal.
An iron ring of 0.25 meter diameter and 2 × 10-3 sq. m. in cross section with a saw cut 1.5 mm wide is wound with 150 turns of copper wire. The air gap flux density is 0.7 Tesla. The relative permeability of iron is 800. Calculate the exciting current. Ignore the leakage.
Answer
Given: Mean diameter D = 0.25 m, Area A = 2 × 10-3 m2, Air gap length lg = 1.5 × 10-3 m, Turns N = 150, Flux density B = 0.7 T, Relative permeability μr = 800.
1. Calculate the length of the iron path (li):
2. Calculate the MMF required for the air gap (Fg):
3. Calculate the MMF required for the iron path (Fi):
4. Total MMF (Ftotal) and Exciting Current (I):
The exciting current required is approximately 9.22 Amperes.
Define the following: (i) node (ii) branch (iii) tree.
Answer
Sign in to view the complete answer paper.
For the network shown in figure 1, obtain the incidence matrix and determine the relationship between loop and branch currents.
Answer
Sign in to view the complete answer paper.
A sinusoidal voltage 25 sin10t is applied at time t= 0 to a series R-L circuit shown in figure 2, consisting of R = 5Ω and inductor L = 1 Henry. Find the value of i (t). Assume no current through the inductor before application of voltage.
Answer
Sign in to view the complete answer paper.
Obtain an expression for transient current in a R-L circuit is suddenly connected with a unit step function by closing the switch at t = 0.
Answer
Sign in to view the complete answer paper.
A series RLC circuit has a quality factor of 5 at 50 rad/sec. The current flowing through the circuit at resonance is 10 A and the supply voltage is 100V. Find the circuit constants.
Answer
Sign in to view the complete answer paper.
Explain different parameters to be considered for design of attenuators.
Answer
Sign in to view the complete answer paper.
Draw the symmetrical T and π sections and their decomposition into L sections.
Answer
Sign in to view the complete answer paper.
The network equations for two- port network give the current I1 and I2 at the two ports as I1 = 0.25V1 – 0.2 V2 and I2 = -0.2V1 + 0.1 V2. Determine the Y and ABCD parameters for the network.
Answer
Sign in to view the complete answer paper.
Find the Z-parameters for the resistive network shown in figure 3.
Answer
Sign in to view the complete answer paper.
Derive the equation of attenuation constant and phase constant of Transmission Line in terms of R, L, C and G.
Answer
Sign in to view the complete answer paper.
Find the reflection coefficient of a 50 Ω transmission line when it is terminated by a load impedance of (60+j 40) Ω.
Answer
Sign in to view the complete answer paper.
Mention the disadvantages of single stub matching.
Answer
Sign in to view the complete answer paper.