Electrical Measurements and Instrumentation MCQs (Part-8)
Which device is used to measure electrical potential difference?
A Ammeter
B Wattmeter
C Voltmeter
D Ohmmeter
A voltmeter is used to measure the potential difference (voltage) between two points in a circuit. It is connected in parallel with the component whose voltage is to be measured. A high internal resistance ensures minimal current draw, preserving the integrity of the circuit.
What does a galvanometer measure?
A Small current
B Power
C Voltage
D Frequency
A galvanometer measures small electric currents with high sensitivity. It works by detecting the magnetic deflection caused by current flowing through a coil placed in a magnetic field. It is commonly used in laboratories for precise measurements of low currents.
Which instrument is used to measure the resistance of a conductor?
A Voltmeter
B Ammeter
C Wattmeter
D Ohmmeter
An ohmmeter is used to measure the electrical resistance of components, circuits, or conductors. By applying a small voltage and measuring the resulting current, it calculates resistance according to Ohm’s Law. This tool is essential for testing circuit continuity and identifying faulty components.
What does an oscilloscope display?
A Frequency
B Waveform
C Power
D Current
An oscilloscope is used to visualize the waveform of an electrical signal. It displays how voltage changes over time, providing engineers and technicians with real time information about signal characteristics, such as amplitude, frequency, and phase. This is essential for troubleshooting and signal analysis.
What is the main function of a bridge circuit?
A Measure resistance
B Measure current
C Measure voltage
D Measure power
A bridge circuit, such as a Wheatstone bridge, is used to measure unknown resistances accurately. It works by balancing two legs of the bridge and calculating the unknown resistance based on the known values. It is crucial for precise resistance measurements in both laboratory and field settings.
Which of the following instruments is used to measure alternating current (AC) power?
A Voltmeter
B Ammeter
C Wattmeter
D Frequency meter
A wattmeter is used to measure the real power consumed by a load in an AC circuit. It measures both voltage and current and calculates the power in watts. It is essential for monitoring and managing electrical energy in industrial and commercial systems.
What is the function of a current transformer (CT)?
A Step up current
B Step down current
C Measure voltage
D Measure power
A current transformer (CT) is used to step down high currents to safer, measurable levels for instruments. It provides electrical isolation and ensures the safety of measuring devices while accurately monitoring current flow in power systems.
What is the primary function of a phase meter?
A Measure frequency
B Measure voltage
C Measure phase difference
D Measure power
A phase meter is used to measure the phase difference between two alternating signals. It helps in analyzing the relationship between voltage and current in AC circuits. Understanding phase differences is essential for optimizing power flow and minimizing losses in electrical systems.
Which device is used to measure the electrical energy consumed over time?
A Energy meter
B Wattmeter
C Ammeter
D Voltmeter
An energy meter is used to measure the total electrical energy consumed over time, typically in kilowatt hours (kWh). It is commonly used by utility companies to track energy consumption for billing purposes and can also help monitor energy efficiency in various settings.
What is the function of a potential transformer (PT)?
A Step up current
B Step up voltage
C Measure power
D Step down voltage
A potential transformer (PT) is used to step down high voltage levels in power systems to a safer, measurable level for instrumentation and protection relays. It is essential for measuring voltage in high voltage systems, ensuring accurate readings while isolating instruments from high voltage circuits.
Which type of instrument is used to measure very high frequency signals?
A Frequency meter
B Oscilloscope
C Spectrum analyzer
D Voltmeter
A spectrum analyzer is used to measure the frequency spectrum of electrical signals. It provides a visual representation of the frequency content of a signal, which is essential in applications like communications, signal processing, and electromagnetic compatibility testing.
What is the purpose of using a potentiometer in a measurement system?
A Measure resistance
B Calibrate voltage
C Measure current
D Measure power
A potentiometer is used for precise measurement and calibration of voltage. By balancing an unknown voltage against a known reference voltage, it allows for accurate voltage measurement. It is often used in laboratories and for precision calibration in electrical systems.
Which of the following instruments measures the current flowing through a circuit?
A Voltmeter
B Wattmeter
C Ammeter
D Multimeter
An ammeter is designed to measure the current flowing through a circuit. It is connected in series with the circuit and is essential for monitoring and troubleshooting electrical systems. There are different types of ammeters for both AC and DC currents.
What does a piezoelectric sensor measure?
A Power
B Strain
C Vibration
D Displacement
A piezoelectric sensor measures mechanical stress, vibration, or acceleration by converting mechanical energy into electrical charge. These sensors are widely used in applications like detecting vibrations in machinery, monitoring structural health, and measuring force or pressure.
What is the main function of a galvanometer?
A Measure current
B Measure voltage
C Measure frequency
D Measure resistance
A galvanometer is a sensitive instrument used to measure small electrical currents. It works on the principle of electromagnetic deflection, where the flow of current through a coil produces a magnetic field that moves a needle. It is often used in precision measurements.