What is the function of the secondary winding in a potential transformer?
A To measure current
B To step down voltage for measurement
C To step up voltage for measurement
D To measure resistance
The secondary winding of a potential transformer reduces high voltage to a safer, measurable value.
Which type of wattmeter is used in DC circuits?
A Induction wattmeter
B Electrostatic wattmeter
C Dynamometer wattmeter
D Thermal wattmeter
Dynamometer wattmeters are versatile and can measure power in both AC and DC circuits.
Which instrument is primarily used to detect small currents?
A Ammeter
B Galvanometer
C Wattmeter
D Voltmeter
Galvanometers are highly sensitive instruments used to detect and measure small electric currents.
What does a digital multimeter display?
A Analog readings
B Digital values of electrical quantities
C Oscillations of current
D Power fluctuations
Digital multimeters display precise numerical values for voltage, current, and resistance on an LCD or LED screen.
What is the typical use of a clamp meter?
A Measure resistance
B Measure current without breaking the circuit
C Measure voltage
D Measure power
Clamp meters measure current by clamping around a conductor, eliminating the need for direct connection.
Which principle does an energy meter use?
A Magnetic induction
B Piezoelectric effect
C Electromagnetic induction
D Electrostatic force
Energy meters work on the principle of electromagnetic induction, with rotating disks proportional to the power consumed.
Which type of frequency meter is most commonly used?
A Digital frequency meter
B Analog frequency meter
C Electrodynamic frequency meter
D Thermal frequency meter
Digital frequency meters are widely used for their accuracy and ability to measure over a wide range of frequencies.
Which type of transformer is used in protective relays?
A Current transformer
B Potential transformer
C Auto transformer
D Distribution transformer
Current transformers reduce high currents to measurable levels for protective relays and meters.
What is the typical range of a household energy meter?
A 0–10 kWh
B 0–100 kWh
C 0–10,000 kWh
D 0–1,000 kWh
Household energy meters are designed to measure energy consumption typically up to 10,000 kWh or more.
What is the working principle of a moving coil instrument?
A Electromagnetic induction
B Electromagnetic deflection
C Electrostatic attraction
D Thermal expansion
Moving coil instruments use electromagnetic deflection, where a current-carrying coil interacts with a magnetic field to produce a deflection.
Which of the following meters is used for three-phase power measurement?
A Single-phase wattmeter
B Three-phase wattmeter
C Digital multimeter
D Galvanometer
A three-phase wattmeter is used to measure power in three-phase circuits, commonly found in industrial systems.
Which of the following is a primary function of a transducer?
A To amplify signals
B To convert one form of energy into another
C To store energy
D To measure resistance
A transducer converts physical quantities (e.g., temperature, pressure) into electrical signals for measurement, processing, or control.
What does a galvanometer measure?
A Voltage
B Current
C Resistance
D Small electric current
A galvanometer is a highly sensitive device used to detect and measure small currents in electrical circuits. It works on the principle of a moving coil in a magnetic field.
Which bridge is used for the measurement of inductance?
A Wheatstone bridge
B Maxwell’s bridge
C Kelvin bridge
D Anderson bridge
Maxwell’s bridge is specifically designed to measure inductance using standard resistors and capacitors, ensuring accurate results in AC circuits.
Which component is used in energy meters for driving their mechanism?
A Inductor
B Commutator
C Electromagnetic coil
D Permanent magnet
Electromagnetic coils create magnetic fields that interact with the rotating disk in energy meters, ensuring the rotation is proportional to the power consumed.
What is the purpose of calibration in instruments?
A To improve accuracy
B To reduce costs
C To change instrument design
D To increase speed
Calibration ensures that measuring instruments provide accurate and reliable results by comparing them to standard references.
Which material is commonly used in strain gauges?
A Copper
B Silicon
C Constantan
D Silver
Constantan is an alloy of copper and nickel. It has a stable resistance over a wide range of strains and temperatures, making it ideal for strain gauges.
Which instrument measures electrical power in a circuit?
A Ammeter
B Voltmeter
C Wattmeter
D Ohmmeter
A wattmeter measures the power consumed in a circuit by simultaneously measuring voltage and current and calculating their product.
What is the function of a current transformer (CT)?
A To step up voltage
B To step down current
C To step down resistance
D To step up power
Current transformers (CTs) reduce high current levels to lower, measurable values for safe metering and protection.
Which device is used to measure frequency in electrical circuits?
A Oscilloscope
B Multimeter
C Frequency meter
D Wattmeter
A frequency meter directly measures the frequency of electrical signals and is commonly used in AC systems.
What is the primary purpose of a potential transformer (PT)?
A To measure resistance
B To step down voltage for measurement
C To amplify signals
D To step up current
A potential transformer reduces high voltages to safe levels, enabling their accurate measurement by meters and protective relays.
Which sensor works on the piezoelectric effect?
A Pressure sensor
B Temperature sensor
C Displacement sensor
D Flow sensor
A piezoelectric pressure sensor generates an electrical signal when subjected to mechanical stress, utilizing the piezoelectric effect.
Which of the following is a dynamic characteristic of an instrument?
A Resolution
B Linearity
C Time constant
D Repeatability
Dynamic characteristics describe how instruments respond to time-varying inputs. The time constant is the time required for a system to reach a certain percentage of its final value.
What does an oscilloscope primarily measure?
A Electric power
B Voltage variations over time
C Frequency
D Resistance
An oscilloscope visually displays voltage changes over time, helping analyze signal waveforms and time-domain characteristics.
What does a thermocouple measure?
A Temperature
B Pressure
C Resistance
D Capacitance
A thermocouple measures temperature by converting the heat difference between its two junctions into an electrical signal.
What is the main function of a signal conditioner?
A To measure current
B To amplify and filter signals
C To store signals
D To transmit signals
Signal conditioners prepare raw signals for further processing by amplifying, filtering, and converting them into a usable format.
What is the main use of a Wheatstone bridge?
A To measure current
B To measure resistance
C To measure voltage
D To measure power
A Wheatstone bridge is a circuit used to measure unknown resistances by balancing two legs of a bridge circuit.
What type of error is caused by environmental factors like temperature and humidity?
A Random error
B Gross error
C Systematic error
D Instrumental error
Systematic errors result from consistent factors such as temperature, pressure, or instrument calibration and can be minimized with corrections.
Which principle is used in LVDT for displacement measurement?
A Electromagnetic induction
B Capacitance variation
C Resistive variation
D Piezoelectric effect
The Linear Variable Differential Transformer (LVDT) uses electromagnetic induction to measure displacement by detecting changes in mutual inductance.
What is the role of a tachometer?
A To measure voltage
B To measure speed
C To measure torque
D To measure frequency
A tachometer is a device used to measure the rotational speed of an object, typically in revolutions per minute (RPM).
Which principle does an ammeter use to measure current?
A Ohm’s Law
B Faraday’s Law of Electromagnetic Induction
C Ampere’s Circuital Law
D Kirchhoff’s Voltage Law
Ammeters measure current by allowing it to pass through a low-resistance shunt, where the voltage drop (according to Ohm’s Law) is used to calculate the current.
What is the purpose of damping in measuring instruments?
A To increase sensitivity
B To reduce oscillations
C To amplify signals
D To measure errors
Damping minimizes the oscillations of the pointer in an instrument, helping it settle quickly to its final reading.
Which type of error occurs due to wear and tear of instrument parts?
A Random error
B Systematic error
C Gross error
D Instrumental error
Instrumental errors result from mechanical defects, wear and tear, or aging of components within an instrument.
What is the main application of a thermistor in electrical measurements?
A Voltage measurement
B Current measurement
C Temperature measurement
D Displacement measurement
A thermistor is a temperature-sensitive resistor whose resistance changes significantly with temperature, making it ideal for temperature measurement.
Which bridge is commonly used for capacitance measurement?
A Kelvin bridge
B Anderson bridge
C Schering bridge
D Wheatstone bridge
Schering bridge is a specialized AC bridge used to measure capacitance and the dielectric loss of a capacitor.
What is the unit of measurement for the sensitivity of a galvanometer?
A Ampere
B Volt
C Ohm
D Microampere per division
Sensitivity of a galvanometer is defined as the smallest current that produces a measurable deflection on its scale.
What does a potentiometer measure?
A Current
B Voltage
C Power
D Frequency
A potentiometer compares an unknown voltage with a known reference voltage to measure the unknown voltage with high precision.
Which of the following is an active transducer?
A Thermocouple
B Strain gauge
C LVDT
D Capacitive sensor
Active transducers generate their output signal directly from the input energy. A thermocouple generates an electrical signal from heat without needing an external power source.
What is the primary use of a phase meter?
A To measure resistance
B To measure the phase difference between signals
C To measure power
D To measure temperature
A phase meter is used to determine the phase angle difference between two periodic signals in an AC circuit.
Which characteristic of a measuring instrument ensures repeated measurements yield consistent results?
A Accuracy
B Precision
C Sensitivity
D Stability
Precision refers to the ability of an instrument to reproduce the same readings consistently under identical conditions.
What is the main purpose of a data acquisition system?
A To amplify signals
B To store signals
C To collect and process data
D To transmit data
Data acquisition systems collect electrical signals from sensors or transducers and process them for analysis or storage.
Which type of noise affects electrical measurements most in industrial environments?
A Thermal noise
B Shot noise
C Electromagnetic interference (EMI)
D Quantum noise
EMI, caused by nearby electrical equipment, can distort signal measurements, making it a significant challenge in industrial environments.
What type of transducer is used to measure displacement?
A LVDT
B Thermistor
C Tachometer
D Wattmeter
Linear Variable Differential Transformers (LVDTs) are used for precise measurement of displacement through changes in inductance.
What does the term “span” refer to in a measuring instrument?
A The minimum value it can measure
B The difference between the maximum and minimum values it can measure
C The accuracy of the instrument
D The rate of response
Span is the range over which an instrument operates, calculated as the difference between the upper and lower limits.
What type of transducer is used to measure pressure?
A Strain gauge
B Thermocouple
C Piezoelectric sensor
D LVDT
Piezoelectric sensors measure pressure by converting mechanical pressure into an electrical signal using the piezoelectric effect.
Which factor affects the accuracy of an energy meter?
A Resistance variation
B Magnetic field interference
C Capacitance of the load
D Phase angle between voltage and current
The accuracy of an energy meter depends on the correct phase relationship between voltage and current, as it measures power consumption.
What is the main use of a Kelvin bridge?
A Measurement of high resistance
B Measurement of low resistance
C Measurement of capacitance
D Measurement of inductance
Kelvin bridge minimizes errors caused by lead and contact resistance, making it ideal for measuring low resistances.
What property of a material is measured using strain gauges?
A Capacitance
B Resistance
C Deformation
D Inductance
Strain gauges measure the deformation (strain) in a material by detecting changes in resistance caused by the strain.
Which type of error is reduced by proper shielding in electrical measurements?
A Systematic error
B Gross error
C Random error
D Environmental error
Proper shielding prevents environmental disturbances like EMI and reduces measurement errors caused by external noise.
What does an RLC meter measure?
A Resistance, inductance, and capacitance
B Voltage and current
C Power and energy
D Frequency and phase
An RLC meter is a precision instrument used to measure the resistance, inductance, and capacitance of electrical components.