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Question 1. Which law states that the sum of the voltages around any closed loop in a circuit equals zero? A) Ohm's Law B) Kirchhoff's Voltage Law (KVL) C) Kirchhoff's Current Law (KCL) D) Thevenin's Theorem Answer: B Explanation: Kirchhoff's Voltage Law (KVL) asserts that the algebraic sum of all voltages in a closed loop is zero, reflecting energy conservation. Question 2. In a series circuit, the total resistance is: A) The sum of individual resistances B) The product of resistances divided by their sum C) Equal to the largest resistor value D) Zero, if resistors are connected in series Answer: A Explanation: Resistors in series add directly, so total resistance equals the sum of all individual resistances.
Question 3. Which component stores energy in an electric field? A) Resistor B) Inductor C) Capacitor D) Diode Answer: C Explanation: Capacitors store energy in an electric field between their plates, which can be released when needed. Question 4. The time constant (τ) for an RC circuit is given by: A) R × C B) R / C C) C / R D) R + C Answer: A Explanation: The RC time constant τ = R × C determines how quickly a capacitor charges or discharges. Question 5. Which device acts as a current-controlled current source? A) Voltage source
B) 90 degrees C) 180 degrees D) 45 degrees Answer: B Explanation: In a purely inductive circuit, voltage leads current by 90°, indicating maximum phase difference. Question 8. The resonance frequency of a series RLC circuit is given by: A) 1 / (2π√(LC)) B) 2π√(LC) C) 1 / (LC) D) L / C Answer: A Explanation: Resonance occurs at frequency f₀ = 1 / (2π√(LC)), where the inductive and capacitive reactances cancel. Question 9. In a BJT, the collector current in the active region is: A) Independent of base current B) Controlled by base current C) Zero in the cutoff region
D) Always equal to emitter current Answer: B Explanation: In the active region, collector current (Ic) is controlled by the base current (Ib), following Ic ≈ β Ib. Question 10. A Zener diode is primarily used for: A) Rectification B) Voltage regulation C) Signal amplification D) Switching Answer: B Explanation: Zener diodes operate in breakdown to maintain a constant voltage, making them ideal for voltage regulation. Question 11. The main advantage of a Darlington pair is: A) Increased voltage gain B) Increased input impedance C) High current gain D) Reduced power consumption Answer: C
Explanation: An ideal op-amp has infinite input impedance (no current drawn) and zero output impedance (can drive any load). Question 14. In a voltage follower configuration, the gain of the op-amp circuit is: A) 0 B) 1 C) - 1 D) Infinity Answer: B Explanation: A voltage follower (buffer) provides a gain of unity, with output voltage equal to input voltage. Question 15. A band-pass filter allows signals within: A) A specific frequency range B) All frequencies C) Only low frequencies D) Only high frequencies Answer: A
Explanation: Band-pass filters pass signals within a certain frequency range while attenuating others. Question 16. The Barkhausen criterion states that sustained oscillations require: A) Zero loop gain B) Loop gain magnitude of 1 and phase shift of 0° or 360° C) Loop gain magnitude of 1 and phase shift of 0° or 360° D) Infinite gain and zero phase shift Answer: C Explanation: Oscillations occur when the loop gain magnitude is 1, and the total phase shift is a multiple of 360°, satisfying Barkhausen's criteria. Question 17. The binary number 1011 is equivalent to which decimal number? A) 11 B) 13 C) 14 D) 15 Answer: B
Explanation: The sum in a full adder is the XOR of its three inputs (A, B, Carry- in). Question 20. A D flip-flop is triggered on: A) Rising edge of clock B) Falling edge of clock C) Both rising and falling edges D) Level of input signal Answer: A Explanation: D flip-flops are typically edge-triggered devices, most commonly triggered on the rising edge of the clock signal. Question 21. The function of a shift register is to: A) Store and shift data serially or in parallel B) Perform binary addition C) Convert analog signals to digital D) Amplify signals Answer: A Explanation: Shift registers store data and shift it serially or in parallel, useful in data transfer and processing.
Question 22. Which device is primarily used to measure the amplitude and frequency of waveforms? A) Multimeter B) Oscilloscope C) Function generator D) Power supply Answer: B Explanation: An oscilloscope visually displays waveforms, allowing measurement of amplitude, frequency, and phase. Question 23. In power electronics, a thyristor is controlled by: A) Voltage applied to its anode B) Gate trigger pulse C) Continuous current flow D) Temperature variation Answer: B Explanation: A thyristor is turned on by applying a trigger pulse to its gate terminal, enabling controlled switching.
Question 26. The purpose of a voltage divider is to: A) Increase voltage B) Decrease voltage to a desired level C) Convert AC to DC D) Filter high-frequency signals Answer: B Explanation: Voltage dividers use resistors to produce a lower voltage proportional to the input voltage. Question 27. The energy stored in an inductor is proportional to: A) Voltage across it B) Current flowing through it squared C) Resistance of the inductor D) Capacitance of the inductor Answer: B Explanation: The energy stored in an inductor is (1/2) L I², proportional to the square of the current. Question 28. Which type of transistor is controlled by a voltage at its gate terminal?
A) BJT
B) JFET and MOSFET C) SCR D) Diode Answer: B Explanation: JFETs and MOSFETs are voltage-controlled devices, with their conduction controlled by gate voltage. Question 29. Which of the following is true about a common-emitter amplifier? A) High input impedance and low output impedance B) High voltage gain and moderate input impedance C) Voltage follower configuration D) Used primarily as a buffer Answer: B Explanation: Common-emitter amplifiers provide high voltage gain and have moderate input impedance, suitable for voltage amplification. Question 30. The impedance of an RLC series circuit at resonance is: A) Zero
D) Magnetic induction Answer: A Explanation: Photodiodes generate current when photons create electron- hole pairs within the semiconductor. Question 33. An ideal transformer has which of the following characteristics? A) No losses and perfect coupling between primary and secondary B) Resistance in the windings C) Variable turns ratio depending on load D) Converts AC to DC efficiently Answer: A Explanation: An ideal transformer has no core losses, zero resistance, and perfect magnetic coupling, enabling efficient voltage and current transformation. Question 34. The function of a buffer amplifier (voltage follower) is to: A) Amplify voltage significantly B) Provide impedance matching with minimal gain C) Perform mathematical addition D) Generate oscillations
Answer: B Explanation: A buffer provides high input impedance and low output impedance, ideal for impedance matching without voltage gain. Question 35. Which logic gate produces a true output only when both inputs are true? A) AND gate B) OR gate C) NOT gate D) NAND gate Answer: A Explanation: AND gate outputs true only if all inputs are true. Question 36. In digital systems, a flip-flop is used to: A) Store binary data B) Perform logical AND operations C) Convert analog signals to digital D) Generate clock signals Answer: A
Explanation: Decoders activate one specific output line corresponding to the binary input, used in selecting memory or peripherals. Question 39. A synchronous counter differs from an asynchronous counter in that: A) It counts based on a common clock signal for all flip-flops B) It counts based on input data lines only C) It does not require a clock signal D) It cannot count beyond 10 Answer: A Explanation: Synchronous counters have all flip-flops triggered simultaneously by a common clock, ensuring synchronized operation. Question 40. Which of the following is a resistive transducer used to measure temperature? A) Thermistor B) Strain gauge C) LVDT D) Piezoelectric transducer Answer: A
Explanation: Thermistors are resistive devices whose resistance varies with temperature, making them suitable for temperature measurement. Question 41. The main function of a multimeter is to measure: A) Voltage, current, and resistance B) Frequency and phase angle C) Power and energy D) Magnetic flux Answer: A Explanation: Multimeters (DMMs) are versatile instruments used to measure voltage, current, and resistance in circuits. Question 42. The primary principle behind an LVDT is: A) Piezoelectric effect B) Electromagnetic induction C) Resistance change with displacement D) Capacitance variation with position Answer: B Explanation: LVDTs operate based on electromagnetic induction, translating linear displacement into electrical signals.
