Electrical Circuit Analysis — DU B.Sc. (Hons) Physics Previous Year Question Papers

Electrical Circuits, Analysis B.Sc. (Hons.) Physics-NEP: UGCF-2022 (a) For the given circuit determine the power dissipated in the resistors : (b) Find the equivalent resistance of the following circuit using Star-Delta transformations: (c) Define inductive reactance. Write it's S.I. units. Plot a graph showing variation of resistance and inductive reactance with change in the frequency of the ac source. (d) (e) Prove that an ideal capacitor does not dissipate power in an ac circuit. Find the form factor for the periodic wave shown below with time period T : ® A series RC circuit with R = 5 kQ and C = 20 LLF has a constant voltage source of 100 V applied at t = 0. Obtain the value of voltage across the capacitor and the resistor for t > 0 if there is no initial charge on the capacitor. 2. (a) Calculate the direction and magnitude of the current through the 5 a resistor between points A and 8 in the given circuit by Nodal analysis method. (7) a) A coil with a self-inductance of 2.4 H and resistance 12 a is suddenly switched across a 120 V DC supply of negligible intemal resistance. Determine the time constant of the coil, the instantaneous value of the current after 0.1 second, the final steady value of the current and the time taken for the current to reach 5 A. (8) 3. (a) In a parallel LCR circuit, the inductance ofo.1 H having a Quality factor of 5 is in parallel with a capacitor. Determine the value of capacitance and coil resistance at resonant frequency of 500 Hz. (7) (b) In a series RL circuit containing pure resistance and pure inductance, the current and the voltage are expressed as : i(t) = 5sin(314t + 27t/3) and v(t) = 15 sin(314t + 57t/6) Determine the values of impedance, resistance, inductance and average power drawn by the circuit. (8) 4. (a) Find the Norton equivalent circuit for the given circuit and calculate the load voltage across 1 kQ resistance. (7) (b) Explain Millman's and Tellegen's theorem for the ac circuits. 5. (a) Find theY-parameters for the following T-network : (b) According to Maximum Power Transfer theorem, what should be the value of load resistance RL to obtain maximum power from the 12 V battery shown in the following circuit? What is the value of this power? (8)