Which type of instrument is used to measure both AC and DC currents?
A Moving Coil Instrument
B Moving Iron Instrument
C Thermocouple Instrument
D Electrodynamometer Instrument
Moving iron instruments can measure both AC and DC currents because they operate on the principle of electromagnetic attraction, which does not depend on the direction of current.
What is the main function of a signal generator?
A To measure frequency
B To produce a test signal
C To amplify voltage
D To measure impedance
Signal generators create various types of signals (sine, square, triangular, etc.) for testing and calibration purposes in electrical circuits.
Which type of transducer is commonly used for torque measurement?
A Strain gauge-based transducer
B Piezoelectric transducer
C Capacitive transducer
D Inductive transducer
Torque measurement often uses strain gauge-based transducers, where strain gauges measure the deformation in a shaft caused by torque.
What does the term “resolution” in instrumentation refer to?
A Maximum measurable value
B Smallest detectable change in input
C Accuracy of the instrument
D Stability over time
Resolution is the smallest input change that an instrument can detect and display, critical for precision measurements.
Which instrument is used to measure very high resistance?
A Multimeter
B Megger
C Ammeter
D Potentiometer
A megger is specifically designed to measure high resistance, such as insulation resistance in electrical equipment.
What is the working principle of a thermocouple?
A Joule’s Effect
B Seebeck Effect
C Faraday’s Law
D Hall Effect
A thermocouple generates an electrical voltage proportional to the temperature difference between its two junctions, based on the Seebeck Effect.
Which error in measurement is caused by sudden changes in ambient temperature?
A Random error
B Environmental error
C Gross error
D Systematic error
Environmental errors arise due to external factors such as temperature, humidity, and pressure affecting the instrument’s performance.
What is the typical application of a Hall effect sensor?
A Current measurement
B Voltage measurement
C Pressure measurement
D Temperature measurement
Hall effect sensors are used to measure current by detecting the magnetic field generated by the current flow.
What is the function of a shunt in an ammeter?
A To decrease sensitivity
B To bypass excess current
C To increase resistance
D To amplify voltage
A shunt is a low-resistance component that diverts a portion of the current away from the ammeter’s sensitive coil, allowing it to measure high currents safely.
What is the principle of operation of an energy meter?
A Electrostatic induction
B Electromagnetic induction
C Piezoelectric effect
D Capacitance variation
Energy meters use electromagnetic induction to measure energy consumption by rotating a disc proportional to the power consumed.
Which method is used for noise reduction in electrical measurements?
A Increasing resistance
B Using shielding and grounding
C Amplifying signals
D Increasing input impedance
Shielding and grounding prevent external electromagnetic interference, reducing noise and improving measurement accuracy.
What is the primary function of a piezoelectric transducer?
A To measure current
B To convert mechanical energy into electrical energy
C To amplify voltage
D To measure capacitance
Piezoelectric transducers generate an electrical signal when subjected to mechanical stress, based on the piezoelectric effect.
Which bridge is used to measure small resistances?
A Maxwell’s bridge
B Kelvin’s bridge
C Schering bridge
D Anderson bridge
Kelvin’s bridge minimizes contact and lead resistance errors, making it suitable for measuring low resistances.
What is the role of a current transformer (CT) in power systems?
A To step down voltage
B To step down current for measurement
C To amplify power
D To convert AC to DC
Current transformers reduce high currents to lower, safer levels for measurement and protection purposes.
Which dynamic characteristic of an instrument describes its ability to follow rapidly changing inputs?
A Accuracy
B Sensitivity
C Response time
D Precision
Response time is the time taken by an instrument to respond to a sudden change in the input signal.
What type of sensor is used for displacement measurement in a capacitive displacement transducer?
A Resistive
B Inductive
C Capacitive
D Piezoelectric
Capacitive displacement sensors measure changes in capacitance caused by variations in the distance between the sensor and the object.
Which type of error occurs due to parallax in analog instruments?
A Gross error
B Systematic error
C Random error
D Environmental error
Parallax errors occur when the observer’s eye is not aligned with the pointer on an analog scale, causing incorrect readings.
What is the main advantage of using a digital multimeter over an analog multimeter?
A Lower cost
B Higher precision and accuracy
C Ease of portability
D Better build quality
Digital multimeters provide more precise and accurate readings with a clear digital display, reducing human errors in reading.
Which property of an electrical signal is analyzed using an oscilloscope?
A Resistance
B Capacitance
C Waveform shape and frequency
D Inductance
Oscilloscopes display the shape and frequency of electrical signals, allowing detailed time-domain analysis.
What is the role of a pressure transducer?
A To measure voltage
B To measure force
C To convert pressure into an electrical signal
D To amplify signals
Pressure transducers use various principles (e.g., piezoelectric, strain gauge) to convert mechanical pressure into an electrical signal for monitoring and control.
What does an analog voltmeter measure?
A Electric current
B Voltage
C Power
D Resistance
An analog voltmeter is designed to measure the potential difference (voltage) across two points in an electrical circuit.
Which of the following is used to measure the rotational speed of a machine?
A Oscilloscope
B Tachometer
C Wattmeter
D Thermistor
A tachometer is used to measure the rotational speed of machines, often in terms of revolutions per minute (RPM).
What is the function of an instrument transformer?
A To measure power directly
B To measure very high voltage or current safely
C To amplify electrical signals
D To reduce resistance
Instrument transformers, such as current transformers (CTs) and potential transformers (PTs), are used to step down high voltage or current to safer levels for measurement and protection.
Which instrument is used to measure the phase difference between two AC signals?
A Ammeter
B Phase meter
C Voltmeter
D Wattmeter
A phase meter measures the phase angle difference between two alternating current (AC) waveforms, providing insight into the synchronization of the signals.
What is the basic principle of an LVDT?
A Variation in capacitance
B Variation in inductance
C Piezoelectric effect
D Resistance change
An LVDT (Linear Variable Differential Transformer) works by detecting changes in inductance as a magnetic core moves within a set of coils, providing accurate displacement measurements.
Which type of error is caused by imperfections in instrument construction?
A Gross error
B Instrumental error
C Random error
D Environmental error
Instrumental errors are caused by design or manufacturing flaws in the instrument, which result in inaccurate readings.
What is the function of a dynamometer-type wattmeter?
A To measure energy directly
B To measure average power
C To measure instantaneous power
D To measure current
A dynamometer-type wattmeter measures the average power in AC or DC circuits using the interaction between fixed and moving coils to calculate power.
What does the term “sensitivity” of a measuring instrument mean?
A The ability to detect small changes in input
B The maximum value it can measure
C The ability to reduce noise
D The speed of measurement
Sensitivity refers to the smallest input change that can be detected by a measuring instrument, making it critical for accurate measurements in small variations.
Which type of noise can be minimized using low-pass filters?
A Thermal noise
B High-frequency noise
C Electromagnetic interference
D Shot noise
Low-pass filters are used to eliminate high-frequency noise by allowing lower frequencies to pass while blocking higher frequencies.
What is the primary function of a Wheatstone bridge?
A To measure resistance
B To measure capacitance
C To measure inductance
D To measure voltage
The Wheatstone bridge is used to measure unknown resistances by balancing two legs of a bridge circuit with known resistances.
What is the main purpose of a load cell?
A To measure temperature
B To measure weight or force
C To measure pressure
D To measure current
Load cells are force transducers that convert applied force into an electrical signal, commonly used for weighing applications.
Which property of a material is measured using a strain gauge?
A Electrical resistance
B Deformation (strain)
C Capacitance
D Thermal conductivity
Strain gauges measure the deformation (strain) in a material by detecting changes in electrical resistance caused by strain.
Which transducer operates on the piezoelectric principle?
A Thermocouple
B Piezoelectric sensor
C LVDT
D Strain gauge
Piezoelectric sensors generate an electrical voltage in response to mechanical stress based on the piezoelectric effect.
What type of error arises from human mistakes during measurement?
A Gross error
B Systematic error
C Random error
D Instrumental error
Gross errors are mistakes made during the measurement process, such as reading the instrument incorrectly or recording wrong data.
What is the main principle of a thermistor?
A Capacitance variation
B Resistance variation with temperature
C Magnetic field induction
D Piezoelectric effect
A thermistor’s resistance changes significantly with temperature, making it an excellent choice for temperature sensing applications.
What is the function of a frequency counter?
A To measure voltage
B To measure the frequency of an electrical signal
C To measure current
D To measure resistance
Frequency counters are used to measure the frequency of electrical signals, often displayed in Hertz (Hz), by counting the number of cycles in a given time period.
Which sensor is used for flow measurement?
A Strain gauge
B Venturi meter
C Tachometer
D Thermistor
A Venturi meter measures fluid flow by detecting pressure differences across a constriction in a pipe, with the pressure drop corresponding to the flow rate.
What is the purpose of calibration?
A To increase the sensitivity of an instrument
B To ensure accuracy by comparing with a standard
C To reduce noise in measurements
D To extend the range of measurement
Calibration is the process of adjusting an instrument to ensure its measurements are accurate by comparing them against a known standard.
Which type of transducer is used for pressure measurement?
A Capacitive transducer
B Thermocouple
C Tachometer
D Multimeter
Capacitive transducers are commonly used to measure pressure by detecting changes in capacitance when pressure is applied to a diaphragm that alters the distance between capacitor plates.
Which error type is minimized by proper shielding in electrical instruments?
A Random error
B Environmental error
C Instrumental error
D Gross error
Proper shielding in electrical instruments helps to reduce environmental errors, such as electromagnetic interference (EMI), which can affect the accuracy of measurements.
What is the primary function of a transducer?
A To amplify signals
B To convert physical quantities into electrical signals
C To store energy
D To measure current
Transducers convert physical parameters like temperature, pressure, or displacement into electrical signals for measurement and control.
Which device is used to measure the power factor of an electrical circuit?
A Wattmeter
B Power factor meter
C Frequency meter
D Ammeter
Power factor meters are specialized instruments used to measure the ratio of real power to apparent power in AC circuits.
What is the principle of operation of an induction-type energy meter?
A Electromagnetic induction
B Piezoelectric effect
C Electrostatic force
D Thermal expansion
Induction-type energy meters work on the principle of electromagnetic induction, where a rotating disc moves proportionally to power consumption.
What is the purpose of using a strain gauge?
A To measure displacement
B To measure strain in materials
C To measure temperature
D To measure pressure
Strain gauges detect changes in resistance caused by strain in materials, allowing for precise measurement of deformation.
What does a signal conditioner do in a measurement system?
A Amplifies and filters the signal
B Measures the signal directly
C Converts analog signals to digital
D Stores the signal
Signal conditioners prepare raw signals from transducers by amplifying, filtering, or converting them into usable forms.
Which instrument is used to detect phase difference between two AC signals?
A Phase meter
B Frequency meter
C Oscilloscope
D Voltmeter
Phase meters measure the angular phase difference between two alternating signals in AC circuits.
What is the primary function of a data acquisition system?
A To store electrical energy
B To collect and process data from sensors
C To measure voltage only
D To transmit data wirelessly
Data acquisition systems gather electrical signals from sensors, process them, and store or display the information.
What type of bridge is used to measure inductance?
A Maxwell’s bridge
B Wheatstone bridge
C Kelvin bridge
D Schering bridge
Maxwell’s bridge is used to measure the inductance of an inductor by balancing the bridge using standard components.
Which transducer is used for measuring temperature?
A LVDT
B Thermocouple
C Strain gauge
D Piezoelectric sensor
A thermocouple generates a voltage proportional to the temperature difference between its two junctions.
What is the unit of power measured by a wattmeter?
A Amperes
B Watts
C Volts
D Ohms
Wattmeters measure power in watts, which is the product of voltage and current multiplied by the power factor.