Electrical Measurements and Instrumentation MCQs (Part-3)
Which device is used to measure electrical resistance?
A Wattmeter
B Ammeter
C Ohmmeter
D Voltmeter
An ohmmeter measures the resistance of a component or circuit. It works by applying a small known voltage to the component and measuring the resulting current. The resistance is then calculated using Ohm’s Law. This is useful in testing electrical components for continuity or fault detection.
What is the primary function of a transducer?
A Convert energy form
B Measure power
C Store energy
D Measure voltage
A transducer converts one form of energy, such as mechanical or thermal energy, into an electrical signal. This conversion is essential for monitoring physical parameters in electrical systems, making them easier to measure and analyze. Common examples include temperature and pressure sensors.
Which instrument is used to measure alternating current (AC)?
A Frequency meter
B Oscilloscope
C Voltmeter
D Ammeter
An ammeter measures the current flowing through a circuit. It is connected in series and typically used to measure both AC and DC currents, depending on its type. For AC measurement, it typically uses a moving coil or shunt mechanism.
What is measured by a galvanometer?
A Power
B Small current
C Voltage
D Resistance
A galvanometer is a sensitive device used to measure small electrical currents. It works on the principle of electromagnetic deflection. Galvanometers are often used in experimental settings and can be part of more complex measuring instruments like wattmeters or multimeters.
Which device is used to measure both AC and DC voltage?
A Multimeter
B Oscilloscope
C Frequency meter
D Voltmeter
A multimeter is a versatile instrument that can measure multiple electrical parameters, including voltage (both AC and DC), current, and resistance. It is widely used in diagnostics, troubleshooting, and routine electrical measurement tasks in labs and industries.
What is the main purpose of an oscilloscope?
A Measure power
B Measure voltage
C Display signal waveform
D Measure frequency
An oscilloscope is used to observe and analyze the waveform of an electrical signal. It displays the signal’s amplitude and frequency over time, which is essential for studying the behavior of electrical circuits, especially in signal processing and communications.
Which of these is used for high voltage measurements?
A Thermocouple
B Wattmeter
C Ohmmeter
D High voltage probe
A high voltage probe is used to safely measure voltages in high voltage circuits. It allows the measurement of electrical potential in environments where standard instruments would be unsafe or impractical. These probes typically include insulation and voltage dividers for safe operation.
What does a frequency meter measure?
A Voltage
B Frequency
C Current
D Power
A frequency meter is an instrument that measures the frequency of an alternating current (AC) signal. It counts the number of complete cycles per second (hertz) of a waveform, providing essential data for analyzing signal characteristics in electrical systems and communication.
Which device measures electrical energy consumption?
A Energy meter
B Voltmeter
C Frequency meter
D Ammeter
An energy meter measures the total electrical energy consumed over a period, usually in kilowatt-hours (kWh). It is typically used by utility companies to bill customers for electricity usage and is also employed in industrial settings to monitor energy efficiency.
Which instrument is used to measure small changes in strain?
A Piezoelectric sensor
B Thermocouple
C Pressure gauge
D Strain gauge
A strain gauge is used to measure small deformations or strain in materials. It works by detecting changes in the electrical resistance of a material when it is stretched or compressed. Strain gauges are essential in mechanical testing and structural health monitoring.
What is the purpose of a current transformer (CT)?
A Step down voltage
B Measure frequency
C Step down current
D Measure power
A current transformer (CT) is used to reduce the high current levels in a power system to a safer, measurable range for instrumentation. It helps in monitoring current without directly exposing instruments to high current flows, ensuring safety and accuracy.
Which instrument measures phase difference between two signals?
A Voltmeter
B Phase meter
C Ammeter
D Wattmeter
A phase meter measures the phase difference between two electrical signals. This is particularly useful in alternating current (AC) systems to analyze the relationship between voltage and current, ensuring that they are in sync for efficient power transfer.
What does a piezoelectric sensor measure?
A Vibration
B Temperature
C Strain
D Pressure
A piezoelectric sensor measures mechanical stress, pressure, or vibration by converting the mechanical energy into electrical charge. This type of sensor is commonly used in applications like detecting vibration, pressure changes, or in sensors for force measurement.
What is a potential transformer (PT) used for?
A Measure resistance
B Step down current
C Step up current
D Step down voltage
A potential transformer (PT) is used to step down high voltages to lower, measurable levels, ensuring safety and accurate voltage measurement. It is used in power systems for monitoring and controlling voltage levels, protecting sensitive equipment from high voltage damage.
Which of the following is used to measure the flow of fluids?
A Thermocouple
B Flow meter
C Strain gauge
D Pressure sensor
A flow meter is an instrument used to measure the flow rate of liquids or gases. It is essential in applications like water treatment, fuel management, and industrial processes where accurate fluid flow measurement is critical for system performance and control.