CPE 302: Measurement and Instrumentation Flashcards

A complete set of vocabulary flashcards covering the concepts, instruments, error analysis, and technologies discussed in the CPE 302: Measurement and Instrumentation course.

Measurement

The process of comparing an unknown quantity with a known standard quantity to evaluate system performance, monitor processes, or verify specifications.

Accuracy

A measurement characteristic that describes how close a measured value is to the true value.

Precision

A measurement characteristic that describes the ability of an instrument to produce consistent results when the same measurement is repeated.

Sensitivity

The ratio of change in instrument output to the change in the measurand input; it indicates how significanly a reading changes with slight changes in the quantity being measured.

Resolution

The smallest change in measurement that an instrument can detect, such as a digital voltmeter detecting changes as small as $1\,mV$.

Sensor

A device that detects a physical quantity and acts as the input element to an instrumentation system.

Transducer

A device that converts a physical quantity (energy) into a measurable electrical signal, such as a thermocouple converting temperature into voltage.

Signal Conditioning Unit

A stage in a measurement system that performs operations such as amplification, filtering, linearization, and analog to digital conversion to process weak signals.

Gross Errors

Errors caused by human mistakes, such as reading an instrument incorrectly, recording wrong data, or using incorrect instrument settings.

Systematic Errors

Predictable errors that occur due to factors like instrument calibration errors, environmental effects, or imperfect instrument design.

Random Errors

Errors that occur due to unpredictable variations such as electrical noise, temperature fluctuations, or mechanical vibrations.

Arithmetic Mean ($\bar{x}$)

The most probable value of a set of measurements, obtained by adding all measured values and dividing by the number of observations: $\bar{x} = \frac{1}{n}\sum_{i=1}^{n} x_i$

Deviation from the Mean ($d_i$)

The difference between an individual measurement and the arithmetic mean: $d_i = x_i - \bar{x}$

Standard Deviation ($\sigma$)

A statistical measure that describes how widely repeated measurement values are spread around the mean: $\sigma = \sqrt{\frac{1}{n}\sum_{i=1}^{n} (x_i - \bar{x})^2}$

Instrument Reliability

The ability of an instrument to perform its function consistently over time with stable readings and minimal drift.

D'Arsonval Galvanometer

A sensitive permanent-magnet moving-coil (PMMC) instrument that produces pointer deflection when a small direct current flows through a coil in a radial magnetic field.

Shunt Resistor ($R_{sh}$)

A low-resistance resistor connected in parallel with a galvanometer to bypass most of the current, allowing the instrument to function as a DC ammeter.

Multiplier Resistor ($R_s$)

A high-value series resistance connected with a galvanometer to limit current and allow the instrument to function as a DC voltmeter.

RMS Value

The Root Mean Square value representing the effective value of an AC signal that produces the same heating effect as a DC signal; for a sine wave: $V_{RMS} = \frac{V_{max}}{\sqrt{2}}$

Electrodynamometer

An instrument that operates based on the interaction between magnetic fields produced by fixed and moving air-cored coils, used to measure both AC and DC.

Wattmeter

An instrument used to measure electrical power; in AC circuits, it measures true power: $P = V I \cos(\phi)$

Wheatstone Bridge

A DC bridge circuit consisting of four resistor arms used to measure an unknown resistance via a null detection principle: $R_x = \frac{R_2 \times R_3}{R_1}$

Maxwell Bridge

An AC bridge circuit used to measure an unknown inductance by comparing it with a standard capacitor.

Schering Bridge

An AC bridge circuit specifically designed to measure capacitance and dielectric loss.

Wien Bridge

An AC bridge used to measure frequency and capacitance, often utilized in audio frequency oscillator circuits.

LCR Meter

An electronic instrument designed to automate the measurement of inductance (L), capacitance (C), and resistance (R) by providing digital readings.

Electronic Voltmeter (EVM)

A device that uses electronic amplification circuits to measure voltage, offering high input impedance to minimize loading effects.

Loading Effect

A phenomenon where a measuring instrument changes the voltage or current in the circuit under test because the instrument itself becomes a parallel resistance branch.

Digital Voltmeter (DVM)

An instrument that measures voltage and displays the result numerically using analog to digital conversion techniques.

Cathode-Ray Oscilloscope (CRO)

An electronic instrument that uses an electron beam to graphically display electrical signals as voltage variations over time.

Time Base Generator

A circuit in an oscilloscope that produces a sawtooth voltage waveform to move the electron beam horizontally across the screen at a uniform rate.

Triggering

A technique used to stabilize an oscilloscope display by ensuring the sweep begins at a specific, predefined point in the signal waveform cycle.

Lissajous Figures

Waveform patterns observed on a CRO used for measuring frequency and phase angles.

Function Generator

An electronic instrument that produces различных periodic electrical waveforms, such as sine, square, triangular, and sawtooth waves.

Smart Sensor

An advanced sensor that integrates a sensing element with built-in signal processing, a microprocessor, and communication interfaces.

Virtual Instrumentation

A measurement system where traditional hardware functions are replaced by software tools and general-purpose computer hardware.