Electrical Measurements and Instrumentation MCQs (Part-10)
What is accuracy in electrical measurements?
A Consistency of results
B Repeatability of measurements
C Closeness to true value
D Ability to measure small values
Accuracy refers to how close a measured value is to the true or accepted value. In electrical measurements, accuracy ensures that the reading closely matches the actual quantity being measured, minimizing errors and improving reliability.
What does precision refer to in measurements?
A Ability to repeat results
B Closeness to true value
C Ability to measure large values
D Sensitivity of the instrument
Precision refers to the consistency or repeatability of measurements. If measurements yield the same or very similar results under the same conditions, the instrument is considered precise, even if it’s not accurate.
What is the main difference between accuracy and precision?
A Accuracy measures the repeatability of results
B Accuracy measures how close a result is to the true value
C Precision measures how close a result is to the true value
D Precision is the ability to measure small values
The key difference is that accuracy reflects how close a measurement is to the actual value, while precision relates to the consistency of repeated measurements. High accuracy means the reading is close to the true value, whereas high precision means repeated measurements yield similar results.
What is a common source of error in electrical measurements?
A Instrument failure
B Environmental conditions
C Human error
D All of the above
Errors in electrical measurements can arise from various sources, including instrument failure, environmental factors (like temperature and humidity), and human error. These factors can distort readings and impact the overall accuracy and precision of measurements.
How can instrument calibration improve measurement accuracy?
A Reduces signal noise
B Increases sensitivity
C Ensures correct scaling of measurements
D Reduces environmental impact
Calibration adjusts an instrument to provide accurate readings by comparing its measurements with a known standard. This ensures that the instrument provides correct values, improving measurement accuracy and reliability for specific applications.
What is the role of an ammeter in an electrical circuit?
A Measure current
B Measure voltage
C Measure power
D Measure resistance
An ammeter is used to measure the amount of electric current flowing through a circuit. It is connected in series with the circuit and provides readings in amperes, helping to monitor and diagnose the current flow in electrical systems.
Which instrument measures the power consumption in an electrical circuit?
A Ohmmeter
B Ammeter
C Wattmeter
D Voltmeter
A wattmeter measures the real power consumed by a load in an electrical circuit. It works by measuring both the current and the voltage and calculating the power in watts, providing critical data for energy management and monitoring.
What is the main purpose of an ohmmeter?
A Measure voltage
B Measure resistance
C Measure current
D Measure power
An ohmmeter is used to measure the resistance of a component or circuit. By applying a small voltage across the component and measuring the current, it calculates the resistance using Ohm’s Law. This tool is essential for testing components and troubleshooting circuits.
How does an oscilloscope display a signal?
A By showing the voltage versus time
B By measuring the current
C By showing resistance values
D By measuring power
An oscilloscope displays the waveform of an electrical signal by plotting the voltage on the vertical axis and time on the horizontal axis. This allows for the visualization of signal amplitude, frequency, and waveform shape, crucial for troubleshooting and signal analysis.
What does a transducer do in a measurement system?
A Amplifies signals
B Filters unwanted signals
C Converts physical quantities into electrical signals
D Measures electrical power
A transducer converts a physical quantity (such as temperature, pressure, or displacement) into an electrical signal that can be measured and analyzed. It is essential in sensors and instrumentation systems, enabling the measurement of non electrical parameters.
What type of error occurs when there is a mistake in instrument reading or operation?
A Gross error
B Systematic error
C Random error
D Environmental error
Gross errors result from mistakes in reading or operating an instrument, such as misinterpretation of data, incorrect calibration, or human error. These errors can be identified and corrected with careful inspection or recalibration.
What does a strain gauge measure in a material?
A Voltage
B Strain
C Pressure
D Displacement
A strain gauge measures the strain, or deformation, in a material when it is subjected to an external force. The gauge detects changes in its electrical resistance as the material stretches or compresses, which can then be used to calculate the strain.
What is the main purpose of a precision resistor in a measurement system?
A Measure current
B Provide accurate voltage
C Set a known resistance value
D Measure power
A precision resistor is used to provide a known, highly accurate resistance value in circuits. It is used in applications like voltage dividers, current measurement systems, and calibration setups to ensure precise and stable resistance values.
What is the main principle of operation for a galvanometer?
A Temperature change
B Resistance change
C Capacitive effect
D Magnetic deflection of a needle
A galvanometer operates on the principle of electromagnetic deflection, where current flowing through a coil in a magnetic field causes a needle to move. It is highly sensitive and is used for measuring small currents.
How can errors in electrical measurements be minimized?
A Using high quality instruments
B Regular calibration
C Proper environmental control
D All of the above
To minimize errors in electrical measurements, high quality instruments should be used, regular calibration should be performed, and proper environmental conditions (such as temperature and humidity) should be maintained. These steps ensure reliable and accurate measurements.