What is the SI unit of electric potential difference?
A Ampere
B Ohm
C Volt
D Watt
Electric potential difference is measured in volts (V), representing the work done to move a unit charge between two points in an electric field.
Which of the following factors affects the inductance of a coil?
A Number of turns
B Length of the coil
C Material of the core
D All of the above
The inductance of a coil depends on the number of turns, the length of the coil, and the permeability of the core material.
What happens to the impedance of an AC circuit with an inductor as the frequency increases?
A Impedance increases
B Impedance decreases
C Impedance remains constant
D Impedance becomes zero
Inductive reactance (XL = 2πfL) increases with frequency, causing the total impedance to increase.
Which electrical quantity is measured by a galvanometer?
A Voltage
B Current
C Power
D Resistance
A galvanometer is a sensitive device used to measure small currents in a circuit.
What type of current is produced by a battery?
A Alternating Current (AC)
B Direct Current (DC)
C Pulsating Current
D Static Current
Batteries produce direct current (DC), where the flow of electric charge is unidirectional.
What is the role of a commutator in a DC machine?
A To generate current
B To convert AC to DC
C To ensure unidirectional current
D To step up voltage
The commutator reverses the current direction in the armature winding of a DC machine, maintaining unidirectional current flow.
Which device is used to measure alternating current (AC) and direct current (DC)?
A Multimeter
B Galvanometer
C Wattmeter
D Oscilloscope
A multimeter is a versatile instrument that can measure AC, DC, voltage, resistance, and sometimes other parameters.
What happens to the resistance of a conductor if its length is doubled?
A Resistance doubles
B Resistance is halved
C Resistance remains the same
D Resistance becomes zero
Resistance (R) is directly proportional to the length (L) of a conductor: R = ρL / A. Doubling L doubles R.
What is the primary function of a choke in a tube light circuit?
A To step up voltage
B To limit current
C To convert AC to DC
D To increase resistance
A choke is an inductor that limits the current in a tube light circuit, ensuring safe and efficient operation.
Which of the following is an application of Ohm’s Law?
A To calculate resistance in a circuit
B To determine the power consumed by a device
C To measure energy
D To step up voltage
Ohm’s Law (V = IR) is used to calculate resistance when voltage and current are known.
What is the primary material used for electrical wiring?
A Aluminum
B Copper
C Steel
D Iron
Copper is widely used in electrical wiring due to its excellent conductivity, ductility, and resistance to corrosion.
What is the purpose of an electrical diagram?
A To measure current
B To visualize the connection of components
C To regulate voltage
D To reduce power loss
Electrical diagrams illustrate the connections and layout of components in a circuit for easy understanding and troubleshooting.
Which safety device is designed to trip when a ground fault occurs?
A Circuit breaker
B Residual Current Device (RCD)
C Fuse
D Transformer
An RCD trips the circuit when it detects leakage current to ground, preventing electric shocks.
Which law governs the relationship between magnetic flux and induced EMF?
A Ohm’s Law
B Faraday’s Law
C Kirchhoff’s Law
D Coulomb’s Law
Faraday’s Law states that the induced EMF in a circuit is proportional to the rate of change of magnetic flux through it.
What happens to the total resistance in a parallel circuit as more resistors are added?
A It increases
B It decreases
C It remains constant
D It becomes zero
Adding resistors in parallel reduces the total resistance, as \( 1/R_{\text{total}} = 1/R_1 + 1/R_2 + \dots \).
What type of current flows in both directions periodically?
A Alternating Current (AC)
B Direct Current (DC)
C Pulsating Current
D Static Current
Alternating current (AC) reverses its direction periodically, following a sinusoidal waveform.
What is the purpose of using a step-down transformer?
A To increase voltage
B To decrease voltage
C To store energy
D To regulate current
A step-down transformer reduces the voltage to a safer or more usable level while increasing current proportionally.
Which device protects electrical appliances from voltage spikes?
A Circuit breaker
B Surge protector
C Fuse
D Resistor
A surge protector shields electrical appliances from voltage spikes by redirecting excess voltage safely to the ground.
What is the unit of electrical power?
A Volt
B Ampere
C Joule
D Watt
Electrical power is measured in watts (W), representing the rate at which electrical energy is consumed or produced.
Which device is used to measure high voltages?
A Multimeter
B Voltmeter
C Megger
D Potential Transformer
A potential transformer is used to measure high voltages by stepping down the voltage to a safe level for measurement instruments.
Which electrical quantity is measured in amperes?
A Voltage
B Current
C Resistance
D Capacitance
Electric current, which is the rate of flow of electric charge, is measured in amperes (A).
What happens to the total capacitance when capacitors are connected in parallel?
A It increases
B It decreases
C It remains constant
D It becomes zero
When capacitors are connected in parallel, their capacitances add up, increasing the total capacitance of the circuit.
What is the primary function of a resistor in a circuit?
A To increase voltage
B To store electrical energy
C To limit current flow
D To step up current
Resistors are used to control the flow of electric current in a circuit, protecting other components from excessive current.
Which device converts mechanical energy into electrical energy?
A Motor
B Generator
C Rectifier
D Transformer
Generators use electromagnetic induction to convert mechanical energy into electrical energy.
What does a capacitor do in a DC circuit?
A Blocks DC and allows AC
B Blocks AC and allows DC
C Increases resistance
D Amplifies voltage
Capacitors block direct current (DC) but allow alternating current (AC) to pass through due to the charging and discharging of their plates.
What is the unit of power in an electrical system?
A Joule
B Watt
C Volt
D Ampere
Power in electrical systems is measured in watts (W), which indicates the rate at which energy is consumed or produced.
What happens to the magnetic field strength inside a coil when the current is increased?
A Increases
B Decreases
C Remains the same
D Becomes zero
The magnetic field strength inside a coil is directly proportional to the current passing through it, so increasing the current strengthens the magnetic field.
What is the function of a rectifier?
A Convert DC to AC
B Convert AC to DC
C Store electrical energy
D Increase current
Rectifiers are used to convert alternating current (AC) into direct current (DC), which is required for many electronic devices.
Which law states that the induced EMF opposes the change in magnetic flux?
A Ohm’s Law
B Kirchhoff’s Law
C Lenz’s Law
D Faraday’s Law
Lenz’s Law states that the direction of the induced EMF is such that it opposes the change in magnetic flux that caused it.
What is the purpose of a circuit breaker?
A Store charge
B Prevent overloading or short circuits
C Measure current
D Increase voltage
Circuit breakers disconnect power automatically during overloading or short circuits to protect the system.
What is the SI unit of inductance?
A Ohm
B Tesla
C Henry
D Farad
Inductance, which measures the ability of a conductor to store energy in a magnetic field, is measured in henries (H).
What does a zener diode primarily do in a circuit?
A Amplifies current
B Converts AC to DC
C Stabilizes voltage
D Regulates current
Zener diodes maintain a constant output voltage across their terminals, making them useful for voltage regulation.
What is the purpose of an ammeter?
A To measure voltage
B To measure resistance
C To measure current
D To measure power
Ammeters measure the electric current flowing through a circuit and are connected in series.
What is the typical value of AC supply voltage in households in India?
A 110 V
B 220 V
C 240 V
D 50 V
The standard AC voltage supply in Indian households is 240 V at a frequency of 50 Hz.
Which of the following is NOT a renewable energy source?
A Solar power
B Wind power
C Fossil fuels
D Hydropower
Fossil fuels like coal and oil are non-renewable energy sources because they take millions of years to form and are depleted faster than they regenerate.
What is the main purpose of a signal generator?
A Measure voltage
B Generate waveforms for testing
C Store electrical energy
D Increase current
Signal generators produce different waveforms, such as sine, square, or triangular, for testing and analysis of electronic circuits.
Which of the following is a good conductor of electricity?
A Rubber
B Glass
C Copper
D Wood
Copper is widely used for electrical wiring due to its excellent conductivity and low resistivity.
What does the term “short circuit” refer to?
A A circuit with low resistance causing high current flow
B A circuit with high resistance blocking current
C A circuit with no voltage
D A disconnected circuit
A short circuit occurs when there is an unintended low-resistance path in a circuit, leading to excessive current flow.
What is the purpose of an isolator in electrical systems?
A Increase voltage
B Protect against overcurrent
C Disconnect a circuit for maintenance
D Store electrical energy
Isolators are used to safely disconnect a circuit from the power supply during maintenance or repair work.
What does the term “electric potential difference” refer to?
A The force between two charges
B The work done to move a charge between two points
C The opposition to current flow
D The power dissipated in a circuit
Electric potential difference is the work done per unit charge to move a charge from one point to another, measured in volts.
What is the SI unit of electric current?
A Volt
B Ohm
C Ampere
D Coulomb
The SI unit of electric current is the ampere (A). It represents the flow of electric charge per second. One ampere is equal to one coulomb of charge passing through a conductor in one second.
Which law states that the current through a conductor is directly proportional to the voltage across it, provided the temperature remains constant?
A Kirchhoff’s Voltage Law
B Ohm’s Law
C Faraday’s Law
D Joule’s Law
Ohm’s Law states \( V = IR \), where \( V \) is voltage, \( I \) is current, and \( R \) is resistance. This relationship holds true as long as the conductor’s temperature remains constant.
What type of circuit allows electric current to flow along multiple paths?
A Series Circuit
B Parallel Circuit
C Open Circuit
D Short Circuit
In a parallel circuit, current can flow through multiple branches. Each branch operates independently, and the voltage across each branch is the same.
Which device is used to measure electric current in a circuit?
A Voltmeter
B Ammeter
C Wattmeter
D Ohmmeter
An ammeter is connected in series with the circuit to measure the flow of current. It has low internal resistance to minimize voltage drop.
What is the function of a fuse in an electrical circuit?
A To increase voltage
B To protect the circuit from overload
C To store energy
D To reduce resistance
A fuse contains a wire that melts when the current exceeds a specified limit, interrupting the circuit and preventing damage from overheating or fire.
In a DC circuit, the power is calculated as:
A \( P = IV \)
B \( P = I^2R \)
C \( P = V^2/R \)
D None of the above
In a DC circuit, power can be calculated using \( P = IV \), \( P = I^2R \), or \( P = V^2/R \), depending on the known quantities.
Which material is commonly used as a conductor in electrical wiring?
A Copper
B Rubber
C Glass
D Wood
Copper is widely used in electrical wiring due to its high electrical conductivity, ductility, and resistance to corrosion.
What happens to the total resistance in a series circuit when more resistors are added?
A It decreases
B It increases
C It remains the same
D It becomes zero
In a series circuit, resistances are added directly: \( R_{\text{total}} = R_1 + R_2 + R_3 + \ldots \). Adding more resistors increases the total resistance.
What is the primary purpose of a transformer?
A To generate electricity
B To measure current
C To change the voltage level
D To store energy
A transformer transfers electrical energy between two circuits using electromagnetic induction and can step up or step down voltage levels.
Which of the following quantities remains constant in a series circuit?
A Current
B Voltage
C Resistance
D Power
In a series circuit, the same current flows through all components since there is only one path for the current.