Electrical Measurements and Instrumentation MCQs (Part-4)
Which instrument is used to measure electrical potential difference?
A Wattmeter
B Voltmeter
C Ohmmeter
D Ammeter
A voltmeter measures the potential difference, or voltage, between two points in a circuit. It is connected in parallel with the component being measured, and its high internal resistance ensures minimal disruption to the circuit. It is essential for analyzing electrical systems and circuits.
What is the primary purpose of an ammeter?
A Measure voltage
B Measure resistance
C Measure power
D Measure current
An ammeter is used to measure the electric current flowing through a circuit. It is connected in series with the load, allowing the current to flow through the ammeter for accurate measurement. It is essential for checking circuit functionality and troubleshooting.
Which instrument is used to measure the resistance of an electrical component?
A Ohmmeter
B Wattmeter
C Volt-Ohmmeter
D Ammeter
An ohmmeter is specifically designed to measure the resistance of a component or conductor. By applying a known voltage and measuring the resulting current, it calculates resistance based on Ohm’s Law. Ohmmeters are critical for diagnosing faults in electrical systems.
Which of the following devices measures power in an AC circuit?
A Ammeter
B Frequency meter
C Wattmeter
D Voltmeter
A wattmeter is designed to measure the real power consumed by a load in an AC circuit. It operates by measuring both the voltage and current in the circuit, allowing it to calculate the actual power being used. This is crucial for efficient power management.
What does a multimeter measure?
A Frequency only
B Voltage, current, resistance
C Only voltage
D Power only
A multimeter is a versatile tool used to measure multiple electrical parameters, including voltage (both AC and DC), current, and resistance. It combines several measuring instruments into one device, making it essential for diagnostics, maintenance, and testing in electrical systems.
Which of the following is used to measure small amounts of current?
A Galvanometer
B Wattmeter
C Ammeter
D Voltmeter
A galvanometer is used to measure very small electric currents with high sensitivity. It operates based on the electromagnetic deflection of a needle in a magnetic field. Galvanometers are commonly used in experiments and precise measurements where small currents need to be detected.
What does a frequency meter measure?
A Power
B Voltage
C Current
D Frequency
A frequency meter measures the frequency of an alternating current (AC) signal. It counts the number of complete cycles per second (Hertz) of a waveform. This is important for ensuring that systems operate at the correct frequency for efficient functioning, especially in power and communications systems.
What is the purpose of a current transformer (CT)?
A Measure power
B Step up current
C Step down current
D Step down voltage
A current transformer (CT) is used to step down high currents to measurable levels, which can then be read by an ammeter or other measuring instruments. CTs provide electrical isolation and ensure the safety of measurement instruments while monitoring large current flows in power systems.
Which instrument is used for high-accuracy voltage measurements?
A Galvanometer
B Potentiometer
C Oscilloscope
D Voltmeter
A potentiometer is an accurate instrument used to measure voltage by balancing it against a known reference voltage. It is often used in calibration and precision measurement settings where high accuracy is required, such as in laboratories or testing environments.
What type of meter is used to measure energy consumption in an electric system?
A Frequency meter
B Multimeter
C Power meter
D Energy meter
An energy meter measures the total electrical energy consumed by a system or device, typically in kilowatt-hours (kWh). It helps monitor energy usage for billing purposes and provides data for improving energy efficiency in residential, commercial, and industrial applications.
What is the main function of a signal conditioner in instrumentation?
A Convert signals
B Filter noise
C Amplify signals
D Convert energy
Signal conditioners adjust or process sensor signals so they can be used by measurement systems. They often convert signals from analog to digital, filter noise, or adjust signal levels, ensuring accurate and reliable data acquisition. They are crucial for improving signal integrity in various measurements.
Which device is used to measure electrical power in a three phase system?
A Energy meter
B Power meter
C Wattmeter
D Phase meter
A wattmeter is used to measure the real power in electrical systems, including three phase systems. It provides accurate readings of power consumed by the load in watts, allowing for efficient power management and system optimization. The three phase wattmeter is designed to handle the complexities of three phase power.
What is the primary function of a strain gauge?
A Measure temperature
B Measure displacement
C Measure pressure
D Measure strain
A strain gauge measures the amount of strain (deformation) in an object when subjected to force. It works by detecting changes in the electrical resistance of a material as it deforms. Strain gauges are essential in structural testing and mechanical load monitoring.
Which of these measures the flow of liquids or gases?
A Flow meter
B Thermocouple
C Pressure sensor
D Strain gauge
A flow meter measures the rate at which liquids or gases move through a pipe or conduit. It is essential for applications like water treatment, fuel management, and industrial processes. Different types of flow meters include mechanical, electromagnetic, and ultrasonic meters.
What is the purpose of an oscilloscope?
A Display waveforms
B Measure frequency
C Measure current
D Measure resistance
An oscilloscope is a device used to visualize the waveform of an electrical signal over time. It helps engineers and technicians analyze signal characteristics, including amplitude, frequency, and phase. This is vital for diagnosing issues in circuits and ensuring proper signal functioning in systems.