Electrical Measurements and Instrumentation MCQs (Part-12)
What is the primary function of a multimeter?
A Measure power
B Measure multiple electrical quantities like voltage, current, and resistance
C Measure temperature
D Measure torque
A multimeter is a versatile device that can measure voltage, current, and resistance, and in some cases, capacitance and frequency.
Which of the following bridges is used to measure low resistance?
A Maxwell bridge
B Kelvin bridge
C Wheatstone bridge
D Schering bridge
The Kelvin bridge is designed to measure low resistances accurately by compensating for contact and lead resistances.
What is the primary application of a galvanometer?
A Measure high currents
B Detect and measure small currents
C Measure frequency
D Measure power
A galvanometer is a sensitive instrument used for detecting and measuring very small electric currents in a circuit.
What is the working principle of a thermocouple?
A Electromagnetic induction
B Seebeck effect
C Piezoelectric effect
D Capacitance variation
A thermocouple operates on the Seebeck effect, where a temperature difference between two dissimilar metals generates a voltage.
Which device is used to measure the electrical power of a circuit?
A Ammeter
B Wattmeter
C Energy meter
D Multimeter
A wattmeter measures the power in an electrical circuit by multiplying the voltage and current, considering the power factor.
What is the unit of electrical power measured by a wattmeter?
A Amperes
B Volts
C Watts
D Ohms
Wattmeters measure power in a circuit in watts, which is the product of voltage and current, adjusted for the power factor.
What does a digital multimeter measure?
A Only current
B Voltage, current, and resistance
C Only resistance
D Frequency only
Digital multimeters are versatile tools that measure voltage, current, and resistance, with many also measuring other parameters like capacitance and frequency.
What is the function of a frequency meter?
A Measure power
B Measure frequency of an electrical signal
C Measure voltage
D Measure capacitance
A frequency meter measures the frequency of an alternating current (AC) signal, typically in Hertz (Hz).
What is the purpose of a current transformer (CT)?
A To step down current for safe measurement
B To step up current for transmission
C To measure voltage
D To store electrical energy
Current transformers (CTs) step down high current values to lower, measurable values for safe measurement and protection purposes in electrical circuits.
What is the function of a potential transformer (PT)?
A Step up voltage for transmission
B Step down voltage for measurement
C Measure current
D Amplify power
Potential transformers reduce high voltage levels to safer, measurable values for use with voltmeters and other measuring instruments.
What is the unit of frequency in a frequency meter?
A Amperes
B Volts
C Hertz (Hz)
D Ohms
Frequency is measured in Hertz (Hz), which represents the number of cycles per second in an alternating current (AC) signal.
What is the main function of a Kelvin bridge?
A Measure low resistance accurately
B Measure inductance
C Measure capacitance
D Measure power
Kelvin bridges are designed to measure low resistances with high accuracy by eliminating errors from lead and contact resistance.
What is the main principle used by a Hall effect sensor?
A Voltage induced by a magnetic field
B Current induced by voltage
C Resistance change with strain
D Capacitance change with temperature
Hall effect sensors detect current by measuring the voltage induced by a magnetic field perpendicular to the current flow.
What is the purpose of using a Venturi meter?
A Measure fluid flow rate
B Measure pressure
C Measure temperature
D Measure voltage
Venturi meters measure the flow rate of fluids by detecting pressure differences across a narrowing section of a pipe.
What type of instrument is used to measure small displacements?
A Thermocouple
B LVDT (Linear Variable Differential Transformer)
C Pressure sensor
D Galvanometer
LVDTs are used for precise displacement measurement by converting mechanical movement into an electrical signal using inductance.
What is the primary function of a piezoelectric sensor?
A Measure temperature changes
B Convert mechanical stress into electrical energy
C Measure voltage changes
D Measure electric current
Piezoelectric sensors generate an electrical signal when subjected to mechanical stress due to the piezoelectric effect.
What does a calibration process ensure in a measuring instrument?
A Increase the accuracy of the instrument
B Ensure that the instrument provides accurate and reliable measurements
C Reduce the size of the instrument
D Improve the signal processing speed
Calibration compares a measuring instrument with a known standard to ensure it provides accurate and reliable results.
What does an oscilloscope primarily measure?
A Voltage waveforms over time
B Current fluctuations
C Frequency response
D Electrical power consumption
An oscilloscope measures voltage signals over time, allowing users to visualize waveforms and analyze signal behaviors.
Which of the following instruments is used to measure very high resistance?
A Ammeter
B Megger
C Voltmeter
D Multimeter
A megger is used for measuring high resistance, especially insulation resistance in electrical systems.
What is the purpose of shielding in electrical measurement systems?
A Reduce electromagnetic interference (EMI)
B Increase signal strength
C Improve accuracy of instruments
D Convert AC to DC
Shielding in electrical systems helps prevent electromagnetic interference (EMI), ensuring more accurate measurements.