University of Mumbai first-year engineering Semester I Basic Electrical & Electronics Engineering paper, June 2025, NEP 2020 scheme, with step-by-step solutions written with AI help and checked.
Mumbai University FE Sem 1 Basic Electrical & Electronics Engineering (ESC102) Question Paper June 2025 (KT)
Written semester papers (NEP 2020 scheme): 60 marks and 2 hours for most first-year courses. Question 1 is compulsory, then any three of questions 2 to 6.
Sections
| Q.1 Attempt all (compulsory) | 5 questions | |
| Q.2 | 2 questions | |
| Q.3 | 2 questions | |
| Q.4 | 3 questions | |
| Q.5 | 3 questions | |
| Q.6 | 3 questions |
Chapters covered
Instructions
Solve on paper with a timer, then check against the solutions.
Q.1 Attempt all (compulsory)
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Q.1 (a) Convert the star circuit into its equivalent delta circuit.
[Figure: star network with centre N; arm N–A = 2 Ω (A at the top), arm N–B = 4 Ω (B at lower left), arm N–C = 6 Ω (C at lower right).]
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Q.1 (b) Write down the relation between line current and phase current, line voltage and phase voltage, power in balanced three phase delta connected balanced load.
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Q.1 (c) Explain the concept of back emf in a DC motor.
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Q.1 (d) What are the losses in a single-phase transformer?
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Q.1 (e) Draw and explain the construction diagram of LED and enlist the applications.
Q.2
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Q.2 (a) Using Norton's theorem, calculate the current through 3 Ω resistor across the terminals A and B in the given circuit.
[Circuit: Top wire: top-left node T → 8 Ω → top-middle node P → 2 Ω → terminal A. A 3 Ω resistor is connected between A and B (right side). Bottom wire: B runs left to bottom-middle node E, then through a 2 Ω resistor to the bottom-left node D. Left branch (T to D): a 15 V battery (+ at the top, toward T) in series with a 2 Ω resistor below it, ending at D. A 16 Ω resistor is connected diagonally from D up to P. Middle branch (P to E): a 5 V battery (+ at the top, toward P) in series with a 10 Ω resistor below it, ending at E.]
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Q.2 (b) Explain the working principle of three phase induction motor and mention its types.
Q.3
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Q.3 (a) An inductive coil having inductance of 0.04 H and resistance 25 Ω has been connected in series with another inductive coil of inductance 0.2 H and resistance 15 Ω. The whole circuit is powered with 230 V, 50 Hz mains. Calculate the power dissipation in each coil and total power factor.
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Q.3 (b) Explain the application of Zener diode as a voltage regulator.
Q.4
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Q.4 (a) Find the current through 4 Ω resistance using Nodal analysis
[Circuit: a common bottom wire (reference). Left branch: a 6 V battery (longer plate, +, at the top) in series with a 3 Ω resistor, going up from the bottom wire to the top-left corner; the top wire runs right to node A. From A a 6 Ω resistor goes down to the bottom wire. Between A and node B (top wire) is the 4 Ω resistor. From B a 2 Ω resistor goes down to the bottom wire. The top wire continues from B to the right, where a 5 A current source (drawn as a filled circle, no arrow shown) is connected between the top-right corner and the bottom wire.]
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Q.4 (b) With the help of a neat circuit diagram explain the operation of a BJT as a switch.
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Q.4 (c) What is the necessary condition for resonance in a series circuit? Derive an expression for resonance frequency.
Q.5
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Q.5 (a) Explain the working principle of single phase transformer and derive the EMF equation.
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Q.5 (b) Explain the working principle of Brushless DC Motor.
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Q.5 (c) A balanced 3-φ, star connected load consist of three coils each consisting of R = 6 Ω and XL = 8 Ω. Determine the 1) Phase impedance 2) Phase voltage 3) Phase current 4) Line current 5) Power factor when connected across 400 V, 50 Hz supply.
Q.6
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Q.6 (a) Using source transformation find the current flowing the 8 Ω resistance
[Circuit: a common bottom wire. Left: an 18 V battery (longer plate, +, at the top) from the bottom wire up to the top-left corner. Top wire: top-left corner → resistor (label printed as 6 Ω, partly over-struck so that it resembles 8 Ω) → node 1 → 6 Ω → node 2 → 1 Ω → terminal X. A 6 Ω resistor goes from node 1 down to the bottom wire. A 2 A current source from the bottom wire up to node 2 (arrow pointing upward, into node 2). The 8 Ω load resistor is connected between X and terminal Y on the bottom wire.]
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Q.6 (b) A coil having a resistance of 10 Ω and an inductance of 40 mH is connected to a 200 V, 50 Hz supply. Calculate the impedance of the coil, current, power factor and power consumed.
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Q.6 (c) Differentiate between BJT and FET.