JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELECTRICAL CIRCUIT ANALYSIS Previous Question Paper (March - 2022 - R18)
Answer any five questions. All questions carry equal marks.
Main
State and explain superposition theorem.
Answer
The Superposition Theorem states that in any linear, bilateral, multi-source network, the response (voltage or current) in any branch is the algebraic sum of the individual responses produced by each source acting alone, while all other independent sources are replaced by their internal impedances.
The steps to apply the theorem are:
- Retain one independent source at a time and replace all other independent voltage sources with a short circuit (0 V) and all other independent current sources with an open circuit (0 A).
- Calculate the desired branch current or voltage due to the single active source.
- Repeat the process for each independent source present in the circuit.
- Find the algebraic sum of all individual responses to obtain the total response.
Using mesh analysis, find the current ‘I’ in the circuit shown in figure 1.
Answer
To find the current I using mesh analysis, define mesh currents in each independent loop. For a circuit with loops 1, 2, and 3, apply Kirchhoff's Voltage Law (KVL) to each loop:
- Assign clockwise currents I1, I2, and I3 to the meshes.
- Write the KVL equation for each mesh by summing the voltage drops across resistors and accounting for voltage sources. For example, in mesh 1: R11*I1 + R12*I2 + R13*I3 = V1, where R11 is the sum of resistances in mesh 1, and R12, R13 are mutual resistances.
- Solve the resulting system of linear equations using Cramer's rule or matrix inversion to find the specific mesh current corresponding to branch I.
- The current I is either equal to a mesh current or the algebraic difference between two adjacent mesh currents depending on the branch location.
State and explain maximum power transfer theorem.
Answer
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Using Thevenin’s theorem, find the current in 10Ω resistor in the circuit shown in figure 2.
Answer
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Derive the expression for the transient current in series RL circuit with AC excitation.
Answer
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Find the expression for the current i(t) in the circuit shown in figure 3. The initial voltage across the capacitor is 10 V and the initial current in the inductor is 5A.
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Derive the expression for the transient current in series RLC circuit with DC excitation.
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In the circuit shown in figure 4, determine the current in the inductor for t > 0. The switch is closed at t = 0.
Answer
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Draw the phasor diagram of series RL circuit with sinusoidal excitation. Explain the relationship between different phasors.
Answer
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Determine RMS and Average values of the waveform shown in figure 5.
Answer
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Draw the phasor diagram of series RLC circuit with sinusoidal excitation. Explain the relationship between different phasors.
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A balanced delta connected load draws 10 kW at a power factor of 0.8 lagging. If the three phase system has a line voltage of 400V, find the impedance of each phase and the total complex power of the load.
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Discuss in detail about the transfer function representation.
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A series combination of resistance of 200Ω and a coil with inductance 1 H and winding resistance 10Ω and a capacitor of 0.5 µF is connected to an AC supply with internal resistance 5 Ω. Find the resonant frequency, quality factor, lower and upper cut off frequencies.
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What are hybrid parameters? How to calculate them?
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For the circuit shown in figure 6, determine impedance parameters.
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