First Year (FE)
- Find 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… Assumption: the direction of the 5 A source is not marked in the figure; it is taken as delivering 5 A upward into node B (the usual form of... 1
- Determine Norton's equivalent circuit which may be used to represent the given network at the terminals AB and hence find current through 5 Ω resistance. [Circuit: a common bottom wire ending at terminal B. Left branch: a 12 V source (circle, + at th… Step 1: Norton current I_N (remove 5 Ω, short A–B). The 4 Ω is then in parallel with 6 Ω across N–B. R_total = 2 + (6∥4) = 2 + 2.4 = 4.4\ Ω... 1
- Compare single-phase and three-phase induction motors. PointSingle-phase induction motorThree-phase induction motor Supply1-phase AC3-phase AC Field producedPulsating field (two counter-rotating... 1
- Explain the construction and working principle of a BLDC motor. Brushless DC (BLDC) motor: a DC-supplied motor in which mechanical commutator and brushes are replaced by electronic commutation. Constructi... 1
- Draw the construction of a DC Motor and label its parts. What are the types of DC Motor? Yoke (outer frame) +---------------------------+ | N pole core + field coil | | \_pole shoe_/ | | .-----------------. | | / armature core \... 1
- Explain CE configuration of BJT with the input and output characteristics. Common-emitter (CE) configuration: emitter is common to input and output. Input is applied between base and emitter (V_BE, I_B); output is t... 1
- Compare BJT and FET PointBJTFET (JFET/MOSFET) CarriersBipolar: both electrons and holesUnipolar: only majority carriers ControlCurrent-controlled device (I_C =... 1
- How an actual (practical) transformer differs from an ideal transformer? Ideal transformerPractical (actual) transformer Windings have zero resistance, so no copper (I²R) loss.Windings have resistance R₁, R₂; copp... 1
- Explain the construction and working principle of a single-phase transformer with a neat labelled diagram. Construction: Core: made of thin (0.35 to 0.5 mm) silicon-steel laminations, insulated from each other by varnish, to reduce hysteresis loss... 1
- Explain working of a LED. LED (Light Emitting Diode): a PN junction diode that emits light when forward biased (electroluminescence). Made of direct band-gap compound... 1
- Draw the characteristics of Zener diode and Explain application of a Zener diode as a voltage regulator Zener diode: a heavily doped silicon PN junction diode designed to operate in the reverse breakdown region without damage. Symbol: diode wit... 1
- Write applications of LED. Applications of LED: Indicator / pilot lamps on electronic equipment, panels and chargers. Seven-segment and dot-matrix displays (calculator... 1
- An alternating current of frequency 50 Hz has a maximum value of 12 A. Find (i) Equation for instantaneous value of current and (ii) Time taken to reach 9.6 A for the first time. Given: f = 50 Hz, I_m = 12 A. ω = 2π f = 100π = 314.16 rad/s. (i) i = I_msinω t ⇒ i = 12sin(314.16 t) A (i.e. 12sin 100π t ). (ii) 9.6 = 12s... 1
- A coil consumes 1 KW power from 50 Hz single phase ac supply and volt-ampere input is 2 KVA. If value of resistance of coil is 10 Ω then find the following parameters with respect to a coil. (i) Value of inductance, (ii) Phase angle, (iii) Power fact… Given: P = 1000 W, S = 2000 VA, R = 10 Ω, f = 50 Hz. Current: P = I²R ⇒ I = √(1000/10) = 10 A. Voltage: V = S/I = 2000/10 = 200 V. (iv) Impe... 1
- Three similar coils each having a resistance of 5 Ω and an inductance of 0.02 H are connected in star to a 440 V, 50 Hz, 3-phase supply. Calculate (i) line current and (ii) active and reactive power Given: R = 5 Ω, L = 0.02 H, star connection, V_L = 440 V, f = 50 Hz. X_L = 2π fL = 2π×50×0.02 = 6.283\ Ω ; Z_ph = √(5²+6.283²) = √(64.48) =... 1
- Two impedances of 12 + j16 Ω and 10 − j20 Ω are connected in parallel across 230 V, 50 Hz, single phase ac supply. Find admittance, current and power factor of each branch. Take V = 230∠0° V. Branch 1: Z₁ = 12 + j16 = 20∠53.13° Ω. Y₁ = 1/Z₁ = 12-j16/12²+16² = 12-j16/400 = 0.03 - j0.04 S = 0.05∠−53.13° S. I₁ = VY... 1
- State the necessary condition for resonance in a series circuit. Compare series and parallel resonance. Condition for series resonance: in an R-L-C series circuit, resonance occurs when the inductive reactance equals the capacitive reactance, X... 1
- Using Superposition theorem, find voltage across 4 Ω resistor. [Circuit: a common bottom wire (reference). Left vertical branch: a 10 A current source between the bottom wire and the top-left wire, arrow pointing upward (current delivered into the to… Take the bottom wire as reference (0 V). Let V_X be the voltage of node X = voltage across the 4 Ω resistor. Step 1: 10 A source acting alon... 1
- State and prove the Maximum power transfer theorem. Derive the formula of Maximum power delivered. Statement: A DC network (linear, bilateral) delivers maximum power to a load resistance R_L when R_L equals the Thevenin (internal) resistan... 1
- Find current flowing through 1 Ω resistance by Node analysis. [Circuit: a common bottom wire (reference). Left vertical branch: a 4 V battery from the bottom wire up to the left node L (longer plate, +, at the top). From L the left vertical wire cont… Reference: bottom wire = 0 V. Node voltages: V_L, V_M, V_R. The 4 V source is directly between L and reference ⇒ V_L = 4 V. KCL at node R (c... 1
- State the function of each constructional part of a DC motor. PartFunction Yoke (frame)Outer cast-iron/steel frame; gives mechanical support and protection, and carries the magnetic flux (return path) b... 1
- Explain the working principle of three phase induction motor. Working principle of a three-phase induction motor: Rotating magnetic field: the stator carries a three-phase winding displaced by 120° in s... 1
- Write short note on any one: (i) Single phase induction motor (ii) BLDC motor. (Answering option (ii); a note on (i) is also given briefly.) Brushless DC (BLDC) motor: a DC-supplied motor in which mechanical commutator... 1
- Explain the application of BJT as an amplifier. BJT as an amplifier (common-emitter, NPN, voltage-divider bias): +Vcc R1 | Rc | +--/\/\/--+------||-----o Vout Vin o--||-+---- B C | Cc2 (to... 1