JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year NETWORK THEORY Previous Question Paper (March - 2022 - R16)
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Main
Describe dot convention with an example.
Answer
The dot convention is a graphical method used to determine the polarity of the induced voltage in mutually coupled coils without requiring detailed knowledge of the winding geometry. A dot is placed at one terminal of each coil. When current enters the dotted terminal of one coil, the induced voltage in the other coil is positive at its dotted terminal.
For example, consider two coils L1 and L2 with mutual inductance M. If current i1 enters the dot of coil 1, the voltage induced in coil 2 is M(di1/dt) with the positive polarity at the dot of coil 2. Conversely, if current leaves the dot, the induced voltage polarity is reversed at the dot.
Obtain an expression for coefficient of coupling between two numbers coupled coils.
Answer
The coefficient of coupling (k) defines the degree of magnetic coupling between two coils, representing the fraction of total flux produced by one coil that links the other.
For two coils with self-inductances L1 and L2 and mutual inductance M, the flux produced by coil 1 is φ1, and the portion linking coil 2 is φ12. Similarly, for coil 2, the flux is φ2 and the portion linking coil 1 is φ21. By definition:
The mutual inductance is given by:
Substituting the flux relationships:
Rearranging for the coefficient of coupling:
Where 0 ≤ k ≤ 1. If k = 1, the coils are perfectly coupled; if k = 0, they are magnetically isolated.
Explain the concepts of self and mutual inductances with an example.
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With an example, obtain the basic tieset matrix for a planar network.
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How active power is measured in three phase system using single wattmeter? Explain.
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A delta-connected load whose phase impedances are ZAB = 50 Ω, ZBC = −j50 Ω, and ZCA = j50 Ω is fed by a balanced Y-connected three-phase source with Vp = 100 V. Find the phase currents.
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Explain the relationship between phase and line quantities in delta connected three phase system.
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A three-phase line has an impedance of (1 + j3) Ω per phase. The line feeds a balanced delta-connected load, which absorbs a total complex power of (12 + j5) kVA. If the line voltage at the load end has a magnitude of 240 V, calculate the magnitude of the line voltage at the source end and the source power factor.
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Derive the expression for the current in series RLC transient circuit exited by sinusoidal supply.
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Derive the expression for the current in series RL transient circuit exited by step input.
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Consider the circuit in figure 1. Given that vo(0) = 2 V, find vo and vx for t > 0.
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How Y-parameters are determined? Explain.
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Find h-parameters for the following two port network shown in figure 2.
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Discuss in detail about the design of high pass filters.
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What is an RC filter? How it works?
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