Electrical Measurements and Instrumentation MCQs (Part-4)
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.