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Question 1. What is the standard SI unit of electric charge? A) Volt B) Coulomb C) Ohm D) Watt Answer: B Explanation: The Coulomb (C) is the SI unit of electric charge, representing the amount of charge transported by a constant current of one ampere in one second. Question 2. Which of the following best defines electric current? A) The rate of flow of charge per unit time B) The potential difference across a resistor C) The opposition to current flow in a circuit D) The energy consumed per unit time Answer: A Explanation: Current is defined as the rate at which electric charge flows through a conductor, measured in amperes (A).
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Question 3. What is the SI unit of electrical potential difference (voltage)? A) Volt B) Coulomb C) Watt D) Henry Answer: A Explanation: Volt (V) is the SI unit of electric potential difference, representing the energy per unit charge. Question 4. Which prefix represents a factor of 10^-3 in scientific notation? A) Mega (M) B) Milli (m) C) Kilo (k) D) Micro (μ) Answer: B Explanation: Milli (m) indicates a factor of 10^-3, meaning one- thousandth.
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Explanation: Using Ohm’s Law, V=IR = 2A × 10Ω = 20V. Question 7. If a circuit has a voltage of 12V and a resistance of 3Ω, what is the current flowing through it? A) 4A B) 36A C) 0.25A D) 15A Answer: A Answer: A Explanation: Current I=V/R = 12V/3Ω=4A. Question 8. Which of the following is the correct expression for electrical power in terms of voltage and current? A) P=VI B) P=V/R C) P=I²R D) P=V²/R
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Answer: A Explanation: Power P is the product of voltage V and current I, P=VI. Question 9. In a simple circuit, if the voltage across a resistor is 9V and the resistance is 3Ω, what is the power dissipated? A) 3W B) 27W C) 81W D) 1/3W Answer: B Answer: B Explanation: P=V²/R = (9V)²/3Ω = 81/3=27W. Question 10. The energy consumed in a circuit operating at 60W for 2 hours is? A) 120 Joules B) 120 Joules per second C) 120 Joules
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B) 10Ω ±5%
C) 100Ω ±5%
D) 1kΩ ±5% Answer: C Answer: C Explanation: Brown=1, Black=0, Red=2 zeros, so 100Ω with ±5% tolerance. Question 13. What is the total resistance of three 4Ω resistors connected in series? A) 12Ω B) 4Ω C) 2Ω D) 16Ω Answer: A Answer: A Explanation: Series resistance sums directly: 4Ω+4Ω+4Ω=12Ω.
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Question 14. In a parallel circuit, if two resistors of 6Ω and 3Ω are connected across the same voltage, what is the equivalent resistance? A) 2Ω B) 1Ω C) 1.8Ω D) 9Ω Answer: C Answer: C Explanation: 1/Req=1/6+1/3=1/6+2/6=3/6=1/2, Req=2Ω. Question 15. Which law states that the algebraic sum of voltages around any closed loop in a circuit is zero? A) Ohm's Law B) Kirchhoff's Voltage Law C) Kirchhoff's Current Law D) Superposition Theorem Answer: B Answer: B
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D) 6Ω
Answer: A Answer: A Explanation: Sum resistances in series: 2Ω+3Ω+5Ω=10Ω. Question 18. In a parallel circuit with resistors of 8Ω and 4Ω, what is the total resistance? A) 2.67Ω B) 12Ω C) 32Ω D) 4Ω Answer: A Answer: A Explanation: 1/Req=1/8+1/4=1/8+2/8=3/8, Req=8/3≈2.67Ω. Question 19. The superposition theorem is applicable when analyzing circuits with: A) A single source
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B) Multiple independent sources C) Only resistors D) Only capacitors Answer: B Answer: B Explanation: Superposition applies when multiple independent sources are present; it allows analyzing each source separately. Question 20. The Thevenin equivalent circuit consists of a voltage source in series with a: A) Resistance B) Capacitance C) Inductance D) Current source Answer: A Answer: A Explanation: Thevenin equivalent simplifies a network to a single voltage source in series with a resistor.
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Explanation: AC waveforms are sinusoidal and vary periodically over time. Question 23. The peak voltage (Vp) of a sine wave is 100V. What is its RMS voltage? A) 70.7V B) 100V C) 141V D) 50V Answer: A Answer: A Explanation: RMS voltage V_RMS=Vp/√2=100/1.414≈70.7V. Question 24. The frequency of a waveform is 50Hz. Its period T is: A) 0.02 seconds B) 50 seconds C) 2 seconds D) 0.5 seconds
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Answer: A Answer: A Explanation: T=1/f=1/50=0.02 seconds. Question 25. Which of the following describes inductive reactance (XL)? A) Resistance to AC caused by inductance, proportional to frequency B) Resistance to AC caused by capacitance, inversely proportional to frequency C) Resistance to DC caused by resistor material D) Opposition to current in a resistor Answer: A Explanation: XL=2πfL; inductive reactance increases with frequency. Question 26. The phase difference between voltage and current in an inductor is: A) Zero B) 90° (leading) C) 180°
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Answer: B Explanation: At resonance, XL=XC, so Z=R. Question 29. The power factor in an AC circuit is defined as the cosine of the: A) Phase angle between voltage and current B) Frequency C) Resistance angle D) Power angle Answer: A Answer: A Explanation: Power factor=cos(θ), where θ is the phase angle between voltage and current. Question 30. Which device is used to convert AC to DC? A) Diode B) Transistor C) Inductor
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D) Capacitor Answer: A Explanation: Diodes allow current to flow in only one direction, making them suitable for rectification. Question 31. The Zener diode is primarily used for: A) Rectification B) Voltage regulation C) Amplification D) Switching high currents Answer: B Explanation: Zener diodes operate in breakdown to maintain a stable voltage, used for voltage regulation. Question 32. A bipolar junction transistor (BJT) in the active region acts as: A) An amplifier B) A switch C) A resistor
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C) The ratio of collector current to emitter current D) The ratio of base current to collector current Answer: A Explanation: β=I_C/I_B, indicating current amplification. Question 35. Which FET type is normally enhanced in mode, requiring a positive gate-source voltage to conduct? A) JFET B) Depletion-mode MOSFET C) Enhancement-mode MOSFET D) Triac Answer: C Explanation: Enhancement-mode MOSFETs require a positive V_GS (for N-channel) to turn on. Question 36. The primary difference between BJTs and FETs is that: A) BJTs are voltage-controlled devices, FETs are current-controlled B) BJTs are current-controlled devices, FETs are voltage-controlled
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C) BJTs are unipolar, FETs are bipolar D) Both are controlled solely by current Answer: B Explanation: BJTs are current-controlled (base current), while FETs are voltage-controlled (gate voltage). Question 37. Which semiconductor device is primarily used as a light emitter? A) Photodiode B) LED C) Zener diode D) SCR Answer: B Explanation: Light Emitting Diodes (LEDs) emit light when forward- biased. Question 38. A silicon controlled rectifier (SCR) is a type of: A) Diode B) Thyristor
