What is the formula for calculating electric current?
A I = V / R
B I = VR
C I = R / V
D I = P / V
According to Ohm’s Law, current (I) is calculated as voltage (V) divided by resistance (R).
What type of current changes direction periodically?
A Direct Current (DC)
B Alternating Current (AC)
C Pulsating Current
D Static Current
AC reverses its direction periodically and is the standard for household and industrial electricity supply.
Which of the following devices is used to measure small electrical resistances?
A Galvanometer
B Wheatstone Bridge
C Multimeter
D Oscilloscope
The Wheatstone Bridge is a precise instrument used for measuring small resistances by comparing them with known resistances.
Which law relates magnetic flux and induced EMF?
A Ohm’s Law
B Coulomb’s Law
C Faraday’s Law of Electromagnetic Induction
D Kirchhoff’s Voltage Law
Faraday’s Law states that a change in magnetic flux induces an electromotive force (EMF) in a conductor.
What does the term “electric power” represent?
A The energy stored in a capacitor
B The rate at which electrical energy is consumed
C The potential difference between two points
D The flow of electrons in a conductor
Electric power is measured in watts (W) and represents the rate of energy consumption or generation in a circuit.
What is the primary function of a rectifier?
A Convert AC to DC
B Store electrical energy
C Regulate voltage
D Amplify signals
Rectifiers are used to convert alternating current (AC) into direct current (DC) for use in electronic devices.
Which of the following is NOT a unit of power?
A Watt
B Joule per second
C Horsepower
D Volt
Volt is the unit of electric potential, while power is measured in watts, joules per second, or horsepower.
Which type of energy conversion takes place in an electrical generator?
A Mechanical to electrical
B Electrical to mechanical
C Chemical to electrical
D Electrical to thermal
Generators convert mechanical energy into electrical energy using electromagnetic induction.
Which material is commonly used for electrical wiring?
A Aluminum
B Copper
C Steel
D Gold
Copper is preferred for wiring due to its high conductivity, ductility, and resistance to corrosion.
What is the purpose of a circuit breaker?
A Step up the voltage
B Prevent overloading or short circuits
C Convert AC to DC
D Regulate current flow
Circuit breakers automatically disconnect power when they detect overcurrent, protecting the circuit and equipment.
Which physical law is the basis for conservation of charge at a node in a circuit?
A Kirchhoff’s Voltage Law
B Kirchhoff’s Current Law
C Ohm’s Law
D Faraday’s Law
Kirchhoff’s Current Law states that the total current entering a node is equal to the total current leaving it, ensuring charge conservation.
What does a capacitor oppose in an AC circuit?
A Voltage
B Current
C Change in voltage
D Resistance
Capacitors resist changes in voltage by storing and releasing charge, which smoothens fluctuations.
Which of the following is a unit of magnetic field strength?
A Weber
B Tesla
C Farad
D Ohm
Magnetic field strength is measured in teslas (T), representing the magnetic flux density.
Which device is used to step up or step down voltage?
A Transformer
B Rectifier
C Inductor
D Capacitor
Transformers modify voltage levels by electromagnetic induction based on the turns ratio of their coils.
What is the purpose of earthing in an electrical system?
A To provide additional current
B To increase voltage
C To protect from electric shock
D To store energy
Earthing provides a safe path for fault currents to flow into the ground, reducing the risk of electric shock.
What is the primary role of a fuse in a circuit?
A To regulate voltage
B To interrupt current during overloading
C To store electrical energy
D To increase resistance
A fuse is a safety device that melts when excessive current flows, breaking the circuit and preventing damage.
Which law relates force, charge, and electric field?
A Coulomb’s Law
B Newton’s Law
C Ohm’s Law
D Kirchhoff’s Law
Coulomb’s Law describes the force between charges, which is proportional to the product of the charges and inversely proportional to the square of the distance between them.
What does the term “electrical conductivity” refer to?
A Resistance to current flow
B Ability to conduct electric current
C Storage of charge
D Blocking of electric current
Electrical conductivity measures a material’s ability to allow the flow of electric current, the reciprocal of resistivity.
What type of circuit has more than one path for current to flow?
A Series circuit
B Parallel circuit
C Short circuit
D Open circuit
A parallel circuit has multiple branches, allowing current to flow through different paths simultaneously.
What is the SI unit of electric charge?
A Joule
B Coulomb
C Ampere
D Watt
Electric charge is measured in coulombs (C), where one coulomb is the charge transported by a current of one ampere in one second.
What is the relationship between voltage and charge in a capacitor?
A Q = VC
B Q = V/C
C Q = C/V
D Q = V²C
The charge (Q) stored in a capacitor is the product of its capacitance (C) and the voltage (V) across it, given by Q = VC.
What happens to resistance when the length of a conductor is doubled?
A Resistance remains the same
B Resistance is halved
C Resistance doubles
D Resistance quadruples
Resistance (R) is directly proportional to the length of the conductor. Doubling the length doubles the resistance.
Which of the following is a passive component?
A Transistor
B Diode
C Resistor
D Operational Amplifier
Passive components like resistors do not require external power to operate, unlike active components like transistors and diodes.
Which property determines the energy storage capacity of a capacitor?
A Inductance
B Capacitance
C Resistance
D Voltage
Capacitance is the measure of a capacitor’s ability to store charge per unit voltage.
What is the primary purpose of an insulator?
A Conduct current
B Resist current flow
C Amplify current
D Convert energy
Insulators like rubber and glass resist the flow of electric current, ensuring safety and preventing short circuits.
Which unit is used to measure electrical energy consumption?
A Watt
B Kilowatt-hour
C Volt
D Joule
Electrical energy consumption is measured in kilowatt-hours (kWh), representing the energy used by a device operating at 1 kW for one hour.
What is the function of a rheostat?
A To measure current
B To adjust resistance
C To store charge
D To amplify voltage
A rheostat is a variable resistor used to control current by varying resistance.
Which physical quantity is represented by the symbol ε₀?
A Magnetic permeability
B Electric permittivity of free space
C Dielectric constant
D Capacitance
ε₀ is the permittivity of free space and is used in equations for electric fields and capacitance.
What happens to total capacitance when capacitors are connected in series?
A Increases
B Decreases
C Remains the same
D Doubles
The total capacitance of capacitors in series is less than the smallest individual capacitance, calculated as 1/Cₜ = 1/C₁ + 1/C₂ + ….
What is the frequency of DC voltage?
A 0 Hz
B 50 Hz
C 60 Hz
D 100 Hz
Direct current (DC) has a constant flow of current and does not vary with time, so its frequency is zero.
What is the role of a voltmeter in a circuit?
A Measure current
B Measure voltage
C Measure resistance
D Measure power
A voltmeter is connected in parallel to measure the potential difference across components in a circuit.
What does the term “dielectric” refer to in a capacitor?
A A conducting material
B An insulating material between capacitor plates
C A material that stores magnetic energy
D A material with high resistance
Dielectrics are non-conducting materials that increase a capacitor’s storage capacity by reducing electric field leakage.
Which phenomenon is used in a transformer?
A Ohm’s Law
B Electromagnetic induction
C Coulomb’s Law
D Kirchhoff’s Law
Transformers use electromagnetic induction to transfer energy between circuits and to change voltage levels.
What is the primary function of a thermistor?
A Convert AC to DC
B Measure temperature
C Store charge
D Adjust frequency
Thermistors are temperature-sensitive resistors that change their resistance with changes in temperature.
What is the term for opposition to AC due to capacitance and inductance?
A Reactance
B Resistance
C Conductance
D Impedance
Impedance is the total opposition to AC, combining resistance and reactance due to inductance and capacitance.
What is the unit of electric flux?
A Weber
B Volt-meter
C Coulomb per meter
D Newton-meter squared per coulomb
Electric flux is measured in Newton-meter squared per coulomb (N·m²/C), representing the electric field lines passing through a surface.
Which material is commonly used for electrical insulation?
A Copper
B Aluminum
C Rubber
D Gold
Rubber is a widely used insulator due to its high resistance and flexibility, making it suitable for protecting wires and cables.
Which type of current does a battery supply?
A Alternating Current (AC)
B Pulsating Current
C Direct Current (DC)
D Static Current
Batteries supply direct current (DC), which flows in a single direction and is used in many portable devices and systems.
What is the formula for energy stored in an inductor?
A (1/2)CV²
B (1/2)LI²
C LI²
D (1/2)QV
The energy stored in an inductor is proportional to the square of the current (I) and the inductance (L), given by E = (1/2)LI².
What does a zener diode do?
A Converts AC to DC
B Allows current in one direction
C Maintains a constant voltage across itself
D Increases resistance
A zener diode is designed to maintain a constant voltage across itself when operating in reverse bias beyond its breakdown voltage, stabilizing voltage in circuits.
What is the relationship between power, current, and resistance?
A P = IR
B P = I²R
C P = R/I²
D P = I/R²
Power (P) dissipated in a resistor is proportional to the square of the current (I) and the resistance (R), expressed as P = I²R.
What is the function of a photodiode?
A Emit light when current flows
B Detect and respond to light
C Convert AC to DC
D Store energy
A photodiode is a semiconductor device that converts light into an electrical signal, commonly used in sensors.
What is the term for materials with no electrical resistance at very low temperatures?
A Conductors
B Insulators
C Superconductors
D Semiconductors
Superconductors are materials that exhibit zero electrical resistance when cooled below a critical temperature.
Which of the following is NOT a source of renewable energy?
A Solar energy
B Wind energy
C Coal energy
D Hydropower
Coal energy is derived from fossil fuels, which are finite and non-renewable resources.
What does the term “electric dipole” refer to?
A A charged particle
B Two equal and opposite charges separated by a distance
C A magnetic field
D A short circuit
An electric dipole consists of two equal and opposite charges separated by a fixed distance, creating an electric field.
Which device is used to store electrical energy in the form of a magnetic field?
A Capacitor
B Inductor
C Resistor
D Transformer
Inductors store energy in their magnetic fields when current flows through them.
What is the main advantage of using a parallel circuit?
A Lower resistance
B Individual control of components
C Increased voltage
D Decreased power consumption
In a parallel circuit, each component operates independently, and a failure in one does not affect others.
What is the SI unit of magnetic permeability?
A Tesla
B Weber
C Henry per meter
D Coulomb per meter
Magnetic permeability is measured in henries per meter (H/m) and describes how a material supports a magnetic field.
What happens to the current in a conductor if the voltage is doubled and resistance remains constant?
A Current doubles
B Current halves
C Current remains constant
D Current becomes zero
According to Ohm’s Law (I = V/R), if voltage (V) doubles and resistance (R) is constant, current (I) doubles.
Which of the following materials has the highest resistivity?
A Copper
B Aluminum
C Rubber
D Gold
Rubber is an insulator with very high resistivity, making it ideal for preventing current flow.