JNTU
JNTU B.Tech II ELECTRICAL CIRCUITS Previous Question Paper (March - 2021 - R13/R15)
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Main
Define the Independent and Dependent Sources? Draw its characteristics.
Answer
An independent source is an active element that provides a specified voltage or current that is completely independent of any other element in the circuit. Its value is constant or a known function of time. The voltage source characteristic is a horizontal line at V volts, and the current source characteristic is a vertical line at I amperes.
A dependent (or controlled) source is an active element where the output voltage or current is controlled by another voltage or current existing elsewhere in the circuit. These are represented by diamond-shaped symbols. There are four types: Voltage-Controlled Voltage Source (VCVS), Current-Controlled Voltage Source (CCVS), Voltage-Controlled Current Source (VCCS), and Current-Controlled Current Source (CCCS). Their characteristics are linear relationships defined by gain constants, such as V = μV_x or I = βI_x.
Determine the current delivered by the source in the circuit shown in Figure 1.
Answer
To determine the current delivered by the source, apply Kirchhoff's Voltage Law (KVL) or Nodal Analysis to the circuit. Assuming a standard single-loop circuit with a source voltage V and resistances R1 and R2 in series, the total resistance is R_eq = R1 + R2. By Ohm's Law, the current I delivered by the source is calculated as:
If the circuit contains multiple loops, identify the loop currents, write the KVL equations for each mesh, and solve the resulting system of linear equations using Cramer's rule or substitution to isolate the current flowing through the source branch.
Illustrate the nodal analysis with suitable example with DC excitation and derive necessary expressions for it? What is the significance of super node?
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Find the mesh currents of the circuit shown in the following Figure 2.
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Define average and effective value of a sine wave. Derive expressions for the same.
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A 200-ohm resistor, a 10 H inductor and a capacitor C are connected in parallel. (i) Find the equivalent impedance at ω = 100 rad/ sec if C= 20µ F, (ii) find the magnitude of the impedance when C= 10µ F, (iii) If the magnitude of the impedance is 125 at ω = 100 rad/ sec, find C and (iv) At what values of ω the magnitude of the impedance equal to 100 Ω if C= 20µ F.
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Explain the term band width and Q for a series circuit. Derive expressions for the same.
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A series circuit consisting of R = 500 ohm, L = 0.5 H, and C = 18 µF is connected to a variable frequency supply of voltage of 120 V. If the frequency is varied through 40 to 80 Hz, draw the locus diagram of current. Determine the current and power factor at 40 and 80 Hz.
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State and explain the Faraday’s laws of electromagnetic induction.
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An iron ring has a mean length of 70 cm and cross-sectional area of 2 cm2. It is wound with 1500 turns. If a current of 2 A flows through the coil, find the flux density in the ring. Assume the relative permeability of iron to be 300. Also calculate current in the coil, if a 2 mm air gap is created in the ring, to have the same flux density in the ring.
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Define the following: (i) Graph (ii) Tree (iii) Basic cut set Matrix (iv) Basic Tie set Matrix.
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Draw the dual of the network shown in Figure 5 and explain the procedure.
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What is maximum power theorem? Derive this theorem for a resistive circuit? Explain the method of using this theorem for a complex network. What is the significance of this theorem.
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Use Thevenin’s theorem to find the current through the 5ohm resistor in below figure 6.
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Dot Convention.
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Concept of self and mutual inductance.
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Coefficient of coupling.
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