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Question 1. Which subatomic particle is primarily responsible for electric charge in atoms? A) Neutron B) Proton C) Electron D) Quark Answer: B Explanation: Protons carry a positive charge and are responsible for the atomic number, which determines the element. Electrons carry a negative charge and are involved in electrical conduction, but protons define the charge of the nucleus. Question 2. In an atom, electrons are arranged in specific regions called: A) Nucleons B) Electron shells or energy levels C) Quark layers D) Orbitals only in the nucleus Answer: B Explanation: Electrons occupy shells or energy levels surrounding the nucleus, which determine their energy state and bonding behavior. Question 3. Materials that allow electric charges to flow freely are classified as: A) Insulators B) Conductors C) Semiconductors D) Dielectrics Answer: B Explanation: Conductors, such as copper and aluminum, permit the free flow of electrons, enabling electricity conduction. Question 4. Which of the following best describes static electricity? A) Continuous current flow in wires
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B) Accumulation of electric charge on the surface of objects C) Magnetic field generated by moving charges D) Flow of electrons in a semiconductor Answer: B Explanation: Static electricity involves the buildup of electric charge on the surfaces of objects, often caused by friction. Question 5. The electric field around a charged object is characterized by: A) The magnetic flux lines B) The force exerted on other charges within the field C) The current in the conductor D) The resistance of the material Answer: B Explanation: The electric field exerts a force on other charges within it, influencing how charges move or interact nearby. Question 6. Voltage is also known as: A) Electric resistance B) Electromotive force (EMF) C) Electric current D) Magnetic flux Answer: B Explanation: Voltage, or EMF, is the potential difference between two points, driving current flow. Question 7. The SI unit of electric current is: A) Volt B) Ohm C) Ampere D) Watt
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Question 11. Ohm's Law states that: A) Voltage equals resistance times current (V=IR) B) Power equals voltage times current (P=VI) C) Resistance equals voltage divided by current (R=V/I) D) Both A and C are correct Answer: D Explanation: Both V=IR and R=V/I are valid forms of Ohm’s Law, relating voltage, current, and resistance. Question 12. If a circuit has a voltage of 12V and a resistance of 4Ω, what is the current? A) 3A B) 48A C) 0.33A D) 16A Answer: A Explanation: Using V=IR, I=V/R=12V/4Ω=3A. Question 13. In a circuit, the power dissipated when voltage is 10V and current is 2A is: A) 20W B) 5W C) 8W D) 12W Answer: A Explanation: Power P=VI=10V×2A=20W. Question 14. Which of the following safety devices is designed to protect a circuit by breaking the connection when excessive current flows? A) Resistor B) Fuse or circuit breaker C) Transformer
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D) Diode Answer: B Explanation: Fuses and circuit breakers disconnect the circuit to prevent damage from overloads or short circuits. Question 15. The purpose of grounding in electrical systems is to: A) Increase voltage B) Protect against electrical shock and facilitate safety C) Reduce current flow D) Insulate the circuit Answer: B Explanation: Grounding provides a safe path for fault currents, reducing shock hazards. Question 16. An open circuit is characterized by: A) Complete path for current flow B) No current flow due to broken connection C) Excess current flow D) Low resistance path Answer: B Explanation: An open circuit has a break in the path, preventing current flow. Question 17. The standard electrical symbol for a resistor in a schematic diagram is: A) A zigzag line B) A rectangle C) A circle with a plus sign D) A straight line Answer: A Explanation: Resistors are symbolized by a zigzag line in schematics.
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B) Kirchhoff’s Voltage Law C) Kirchhoff’s Current Law D) Faraday’s Law Answer: C Explanation: Kirchhoff’s Current Law (KCL) states that the total current entering a junction equals the total current leaving. Question 22. A voltage divider circuit is used primarily to: A) Increase voltage B) Obtain a lower voltage proportional to the input voltage C) Convert AC to DC D) Divert current to ground Answer: B Explanation: Voltage dividers produce a specific fraction of the input voltage for measurement or biasing purposes. Question 23. Which of the following best describes a magnet’s north pole? A) The pole that attracts south magnetic poles B) The pole that repels south magnetic poles C) The pole that always points south D) The pole that produces a magnetic field pointing outward from the north pole Answer: A Explanation: North poles attract south poles, which is fundamental to magnetic interactions. Question 24. Magnetic flux lines: A) Indicate the direction and strength of magnetic fields B) Are always circular around conductors C) Are only present in ferromagnetic materials D) Are the same as electric field lines
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Answer: A Explanation: Magnetic flux lines show the direction and relative strength of magnetic fields. Question 25. An electromagnet’s magnetic field is strongest at: A) The center of the coil B) The poles of the electromagnet C) The outside of the coil D) The core of a non-conductive material Answer: B Explanation: The magnetic field is concentrated and strongest at the poles of an electromagnet. Question 26. Faraday’s Law states that: A) A changing magnetic flux induces an electric current in a conductor B) Magnetic poles always come in pairs C) Electric current produces a magnetic field D) Electric fields are produced by moving charges Answer: A Explanation: Faraday’s Law explains electromagnetic induction: a change in magnetic flux induces a voltage. Question 27. Lenz’s Law indicates that: A) The induced current opposes the change in magnetic flux that produced it B) Magnetic poles attract or repel each other C) Magnetic field lines always form closed loops D) The induced voltage is proportional to the flux change Answer: A Explanation: Lenz’s Law states that the direction of induced current opposes the change causing it. Question 28. A solenoid is primarily used to:
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Answer: A Explanation: RMS (Root Mean Square) voltage for a sine wave is Vp/√2, representing the equivalent DC value. Question 32. Inductive reactance (XL) increases with: A) Increasing frequency B) Decreasing frequency C) Increasing resistance D) Decreasing inductance Answer: A Explanation: XL = 2πfL; as frequency increases, inductive reactance increases proportionally. Question 33. The phase relationship between voltage and current in an inductor is: A) Voltage leads current by 90° B) Voltage lags current by 90° C) Voltage and current are in phase D) Voltage leads current by 180° Answer: A Explanation: In an inductor, the voltage leads the current by 90°, due to energy storage in the magnetic field. Question 34. The capacitive reactance (XC) of a capacitor decreases as: A) Frequency increases B) Frequency decreases C) Capacitance decreases D) Resistance increases Answer: A Explanation: XC = 1/(2πfC); as frequency increases, XC decreases.
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Question 35. In an RC circuit, the current is maximum at: A) The moment the circuit is completed B) When the capacitor is fully charged C) When the voltage is zero D) When the resistor is disconnected Answer: A Explanation: Initially, at the moment of closing, the capacitor is uncharged, allowing maximum current. Question 36. The impedance of a series RLC circuit at resonance is: A) Equal to the resistance only B) Zero C) Maximum D) Equal to the reactance of the inductor or capacitor Answer: A Explanation: At resonance, the reactive effects cancel, leaving impedance equal to resistance. Question 37. The Q factor of a resonant circuit indicates: A) The bandwidth relative to the resonant frequency B) The total resistance in the circuit C) The quality of the power supply D) The voltage across the inductor only Answer: A Explanation: Q factor measures the sharpness of resonance; higher Q means narrower bandwidth. Question 38. A diode allows current to flow: A) Only in the forward bias direction B) Only in the reverse bias direction C) Both directions equally
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Question 42. In an NPN transistor, the majority charge carriers are: A) Electrons B) Holes C) Ions D) Protons Answer: A Explanation: In NPN transistors, electrons are the majority carriers in the n-region. Question 43. A common emitter configuration in transistors is primarily used for: A) Voltage amplification B) Current switching C) Voltage regulation D) Signal filtering Answer: A Explanation: The common emitter configuration provides voltage amplification with a phase inversion. Question 44. An operational amplifier (op-amp) configured as a voltage follower provides: A) Unity gain with no amplification B) Maximum gain C) Inverted output D) Oscillations Answer: A Explanation: A voltage follower provides buffering with a gain of 1, replicating input voltage at output. Question 45. The main advantage of integrated circuits (ICs) over discrete components is: A) Miniaturization and reliability B) Higher power consumption C) Larger size
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D) Reduced functionality Answer: A Explanation: ICs are compact, reliable, and allow complex circuits to be fabricated on small chips. Question 46. Which of the following is a typical function of a 555 timer IC? A) Generating precise time delays or oscillations B) Amplifying audio signals C) Rectifying AC to DC D) Voltage regulation Answer: A Explanation: The 555 timer is widely used for generating accurate time delays and oscillations. Question 47. Which component is used to convert AC to DC in power supplies? A) Transformer B) Rectifier (diodes) C) Inductor D) Capacitor only Answer: B Explanation: Rectifiers, composed of diodes, convert AC to pulsating DC. Question 48. The primary purpose of a fuse in an electrical circuit is: A) To prevent overcurrent damage B) To regulate voltage C) To step up voltage D) To store electrical energy Answer: A Explanation: Fuses protect circuits by melting and disconnecting when current exceeds safe levels.
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D) Stable isotope formation Answer: B Explanation: Valence electrons are the outermost electrons involved in bonding and conduction. Question 53. An insulator is characterized by: A) High resistance to electric current B) Low resistance to electric current C) Conducts electricity easily D) Contains free electrons for conduction Answer: A Explanation: Insulators have high resistance, preventing free flow of electrons. Question 54. Static electricity is caused by: A) Moving charges in a wire B) Imbalance of electric charges on surfaces C) Magnetic field variations D) Flow of electrons in a circuit Answer: B Explanation: Static electricity results from an imbalance of charges on surfaces, often caused by friction. Question 55. The electric potential difference between two points is measured in: A) Amperes B) Ohms C) Volts D) Watts Answer: C Explanation: Voltage, or potential difference, is measured in volts.
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Question 56. The SI unit of electric resistance is: A) Volt B) Ampere C) Ohm D) Watt Answer: C Explanation: Resistance is measured in ohms (Ω). Question 57. When a resistor has a resistance of 10Ω and a current of 2A flows through it, the voltage across it is: A) 5V B) 20V C) 10V D) 2V Answer: B Explanation: V=IR; V=10Ω×2A=20V. Question 58. Power dissipation in an electrical component is given by: A) P=VI B) P=I²R C) P=V²/R D) All of the above Answer: D Explanation: All formulas are correct depending on the known quantities. Question 59. Which law states that the sum of the currents entering a junction equals the sum leaving? A) Ohm’s Law B) Kirchhoff’s Current Law C) Kirchhoff’s Voltage Law
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Question 63. In a parallel circuit, the total resistance of R1=4Ω and R2=6Ω is: A) 2.4Ω B) 10Ω C) 24Ω D) 1.5Ω Answer: A Explanation: 1/RT= 1/4Ω+ 1/6Ω= (3/12)+(2/12)=5/12; RT=12/5= 2.4Ω. Question 64. The voltage across all components in parallel is: A) The same for each component B) Divided proportionally C) Zero D) Equal to the sum of individual voltages Answer: A Explanation: Voltage remains constant across parallel branches. Question 65. Kirchhoff’s Voltage Law states that: A) The total voltage around a closed loop is zero B) The sum of currents at a junction is zero C) Voltage drops are proportional to resistance D) Voltage is always positive Answer: A Explanation: The law states the algebraic sum of all voltages in a closed loop is zero. Question 66. A voltage divider circuit is often used to: A) Provide a reduced voltage from a higher voltage source B) Increase voltage for appliances C) Rectify AC signals
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D) Measure current directly Answer: A Explanation: Voltage dividers decrease voltage to desired levels. Question 67. Magnetic poles are always found in pairs called: A) North and South poles B) Positive and Negative poles C) Electric and Magnetic poles D) Inductive and Capacitive poles Answer: A Explanation: Magnetic poles always come in pairs—north and south. Question 68. Magnetic flux lines: A) Show the direction of magnetic force B) Are always straight C) Cross each other at poles D) Are only present in ferromagnetic materials Answer: A Explanation: Flux lines indicate the direction and strength of magnetic fields. Question 69. The magnetic field around a current-carrying wire: A) Forms concentric circles around the wire B) Is uniform in all directions C) Is strongest at the wire’s ends only D) Does not depend on current magnitude Answer: A Explanation: Magnetic field lines form concentric circles around the conductor with their density indicating strength.
