JNTU
JNTU B.Tech I BASIC ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (May - 2019 - R16)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
State Kirchoff’s laws.
Answer
Kirchhoff's Current Law (KCL) states that the algebraic sum of currents meeting at any junction or node in an electrical circuit is zero. Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around any closed loop in a circuit is zero.
Draw the wave forms for voltage, current of pure inductor when excited by a sinusoidal voltage.
Answer
In a pure inductor, the current lags the voltage by 90 degrees. The voltage waveform is a sine wave, v(t) = Vm sin(ωt), and the current waveform is a negative cosine wave, i(t) = Im sin(ωt - 90°).
State maximum power transfer theorem.
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Derive the expression for resonant frequency of a RLC series circuit.
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Draw the V-I characteristic of a PN diode and show the shift with increase in temperature.
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What is the purpose of using filters with rectifiers?
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Define hie and hre.
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What are the demerits of fixed bias method of a transistor?
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Explain principle of operation of SCR.
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Compare BJT and FET.
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Part B
Differentiate dependent and independent sources.
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Find the power in 30Ω resistance using nodal analysis for the circuit shown in figure 1.
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A wire carries a current, which is a combination of a d.c current of 10A and a sinusoidal current with a peak value of 10A. Determine RMS value of the resultant.
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An impedance z1 = 6+j8 Ω is connected in series with a parallel combination of impedances z2 = 10+j6 Ω, z3 = 8-j10 Ω and is connected to a 300V, 50Hz supply. Find the total active power, reactive power and power factor of the circuit.
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A series RLC circuit with R = 100Ω, L = 0.6H and C = 45µF is applied a voltage of 100 ∠ 0° V with variable frequency. Calculate resonant frequency, current at resonance, voltage across R, L and C at resonance.
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Derive the expression for half power frequencies of a RLC series resonant circuit.
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For the circuit shown in the figure 2 draw current locus diagram.
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By using superposition theorem find the current in the 6Ω resistance of the following circuit shown in figure 3.
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Define the terms dynamic resistance of a diode and ‘Diffusion capacitance of a diode’.
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Explain how capacitor filter improves the performance of a full wave rectifier.
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Compare the characteristics of centre tapped transformer type and bridge type full wave Rectifiers.
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Draw the equivalent circuit and V-I characteristic of ideal and piecewise linear model of a PN junction diode.
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Draw the simplified h-parameter equivalent circuit of BJT in CB configuration and derive expressions for Av, Ai, Zi and Zo.
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Explain how bias stabilization and compensation are done using diodes.
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Explain voltage divider biasing method with relevant circuit diagrams and equations.
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Compare CE, CB and CC characteristics of a BJT.
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Explain the construction and principle of operation of JFET.
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Explain how zener diode acts as a voltage regulator.
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Draw the energy band diagram of tunnel diode and explain tunneling phenomenon. Draw its V-I characteristics.
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Explain the working principle of varactor diode.
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