Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II ELECTRICAL CIRCUIT ANALYSIS Previous Question Paper (September - 2021 - R18)
Answer any five questions. All questions carry equal marks.
Main
State and explain reciprocity theorem in detail.
Answer
The Reciprocity Theorem states that in any linear, bilateral, passive network, the ratio of the response (current or voltage) in one branch to the excitation (voltage or current) in another branch remains the same if the positions of the excitation and response are interchanged.
For a network with a single voltage source V in branch 1 producing current I in branch 2, if the source is moved to branch 2, it will produce the same current I in branch 1. The network must be linear (parameters do not change with voltage/current), bilateral (parameters are independent of direction), and passive (no independent sources other than the one being interchanged).
Using Mesh analysis, find V and I in the circuit below figure 1.
Answer
To solve for V and I using Mesh analysis, follow these steps:
- Assign clockwise mesh currents I1, I2, ..., In to each independent loop in the circuit.
- Apply Kirchhoff's Voltage Law (KVL) to each mesh: ∑V = 0. For a mesh with a current Ix, the sum of voltage drops across all resistors equals the sum of voltage sources in that loop.
- Account for shared components: if a resistor R is shared between mesh 1 and mesh 2, the voltage drop is R(I1 - I2) or R(I2 - I1) depending on the loop direction.
- Solve the resulting system of linear equations to find the values of all mesh currents.
- Calculate the required branch current I by taking the algebraic sum of the mesh currents passing through that specific branch.
- Determine the voltage V across the specified component using Ohm's Law: V = Icomponent × Rcomponent.
By systematically applying these equations, the unknown current I and voltage V are uniquely determined based on the circuit parameters provided in the figure.
State and Explain Thevenin’s theorem in detail.
Answer
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Find the maximum power transferred to load resistance RL in the circuit below figure 2.
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Derive the expression for the complete response for the voltage across resistor in parallel RL circuit excited by DC supply at t = 0.
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In the circuit below figure 3, find i(0+), di(0+)/dt and d2i(0+)/dt2.
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Derive the expression for the complete response for the current in a series RC circuit excited by sinusoidal supply by closing the switch at t = 0+.
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For the circuit given below figure 4, V0=10V and the inductor is initially relaxed. The switch S is closed at t=0. Derive the expression for ‘i’.
Answer
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Prove that the line current is √3 times the phase current in three phase delta connected balanced system.
Answer
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A resistance of 10 Ω is connected in parallel with a 2 µF capacitor and the network is connected to a 120V, 60Hz supply. Determine the current and power in resistor and capacitor.
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Derive the expression for average power in a linear circuit (R-L) excited by sinusoidal voltage source.
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Three 10 Ω resistors are connected in delta across a 150V, 50Hz, 3-φ supply. Find the line current. Determine the value of resistance that must be connected in star in order to take the same line current.
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Derive the expressions for current and impedance in series RLC circuit at resonance.
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What are the basic properties of Laplace transforms? Explain.
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Derive the relationship between hybrid and transmission parameters.
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For the circuit below figure 5, determine impedance parameters.
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