JNTU
JNTU B.Tech II ELECTRICAL CIRCUITS Previous Question Paper (September/October - 2023 - R15)
Answer all questions in Part A. Answer any one question from each unit in Part B.
Part A
What are the different types of elements?
Answer
Electrical elements are primarily classified into two categories: Active elements and Passive elements.
Active elements are capable of generating or delivering energy to a circuit, such as voltage sources and current sources. Passive elements are those that consume, store, or dissipate energy, such as resistors (which dissipate energy as heat), inductors (which store energy in a magnetic field), and capacitors (which store energy in an electric field).
Distinguish between Ideal and practical sources.
Answer
An ideal voltage source maintains a constant terminal voltage regardless of the current drawn from it, implying zero internal resistance. In contrast, a practical voltage source has a small internal series resistance, causing the terminal voltage to decrease as the load current increases due to the internal voltage drop.
Similarly, an ideal current source delivers a constant current to any load connected to it, implying infinite internal resistance. A practical current source possesses a finite internal shunt resistance, which causes the output current to vary depending on the load resistance connected across its terminals.
Define power factor.
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What is the significance of j notation?
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Define self-inductance.
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State Faraday’s laws of electromagnetism.
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Define the following: i) Graph ii) Tree.
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What are the dual elements of R, L, C and G?
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State Maximum Power Transfer Theorem.
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State Compensation theorem.
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Part B
Explain in detail about the source transformation with the help of necessary examples.
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Find the values of V1 and V2 in the network shown using Nodal method of Analysis (figure 1).
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Determine the voltage drop across the 8 ohms resistor in the circuit shown figure 2 using Kirchoff’s law.
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Using nodal analysis, determine the Power supplied by 8V Voltage source (figure 3).
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Explain why current leads the voltage by 90 degrees in case of ideal capacitor.
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A coil having a resistance of 20 ohms and an inductance of 0.2 H is connected in series with a 50 µF capacitor across a 250 V, 50 Hz supply. Calculate (i) the current (ii) the power (iii) the power factor (iv) the voltage across the coil and capacitor. Draw the phasor diagram.
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Define RMS value and Average value of an alternating quantity. Determine these values for a full wave rectified sine wave.
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Find the average value, r.m.s value for the wave form shown in figure 4.
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Define Q-factor. Derive an equation showing the relation between Q-factor and Band width. What is selectivity and how it is related to Q-factor.
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A series RLC circuit with R=100Ω, L = 0.5H, C=40µF has an applied voltage of 100∠0 degrees with variable frequency. Calculate the resonance frequency, current at resonance and voltage across R, L, and C. Also calculate the Q-factor, upper and lower cutoff frequencies.
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Show that the locus of the current in an R-L circuit with XL variable is a semicircle. Find the radius and the center of the circle.
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A coil of 20 ohms resistance and inductance of 0.2H is connected in parallel with a capacitor of 100 µF. Determine the resonant frequency and input impedance at Resonance.
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Explain in detail about Nodal method of analysis of Networks with dependent and independent voltage and current sources.
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What is duality? Explain the procedure for obtaining the dual of the given planar network shown below figure 5.
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Find the Thevenins’s equivalent circuit of the circuit shown below figure 6 across the terminals a, b. And also find the current through RL = 16 ohm.
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Obtain Norton’s Equivalent for the circuit shown figure 7 with respect to terminals A and B.
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Determine the current I in the circuit shown figure 8 using Superposition Theorem.
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Calculate the current flowing through RL = 20 of the network shown in the figure 9 by using Thevenin’s theorem.
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