List of measuring instruments


A measuring instrument is a device to measure a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item under study and the referenced unit of measurement. Measuring instruments, and formal test methods which define the instrument's use, are the means by which these relations of numbers are obtained. All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty.
These instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators. Virtual instrumentation is widely used in the development of modern measuring instruments.

Time

In the past, a common time measuring instrument was the sundial. Today, the usual measuring instruments for time are clocks and watches. For highly accurate measurement of time an atomic clock is used.
Stopwatches are also used to measure time in some sports.

Energy

Energy is measured by an energy meter. Examples of energy meters include:

Electricity meter

An electricity meter measures energy directly in kilowatt-hours.

Gas meter

A gas meter measures energy indirectly by recording the volume of gas used. This figure can then be converted to a measure of energy by multiplying it by the calorific value of the gas.

Power (flux of energy)

A physical system that exchanges energy may be described by the amount of energy exchanged per time-interval, also called power or flux of energy.
*
For the ranges of power-values see: Orders of magnitude (power).

Action

Action describes energy summed up over the time a process lasts. Its dimension is the same as that of an angular momentum.
  • A phototube provides a voltage measurement which permits the calculation of the quantized action of light.

Geometry

Dimensions (size)

Length (distance)

For the ranges of length-values see: Orders of magnitude (length)

Area

For the ranges of area-values see: Orders of magnitude (area)

Volume

If the mass density of a solid is known, weighing allows to calculate the volume.
For the ranges of volume-values see: Orders of magnitude (volume)

Angle

Orientation in three-dimensional space

See also the section about [|navigation] below.

Level

Direction

Coordinates

Mechanics

This includes basic quantities found in classical- and continuum mechanics; but strives to exclude temperature-related questions or quantities.

Mass or volume flow measurement

Speed or velocity (flux of length)

For the ranges of speed-values see: Orders of magnitude (speed)

Acceleration

Mass

For the ranges of mass-values see: Orders of magnitude (mass)

Linear momentum

Force (flux of linear momentum)

Pressure (flux density of linear momentum)

For the ranges of pressure-values see: Orders of magnitude (pressure)

Angular velocity or rotations per time unit

For the value-ranges of angular velocity see: Orders of magnitude
For the ranges of frequency see: Orders of magnitude (frequency)

Torque

Energy carried by mechanical quantities, mechanical work

Electricity, electronics, and electrical engineering

Considerations related to electric charge dominate electricity and electronics.
Electrical charges interact via a field. That field is called electric field.If the charge doesn't move. If the charge moves, thus realizing an electric current, especially in an electrically neutral conductor, that field is called magnetic.
Electricity can be given a quality — a potential. And electricity has a substance-like property, the electric charge.
Energy in elementary electrodynamics is calculated by multiplying the potential by the amount of charge found at that potential: potential times charge.

Electric charge

For the ranges of charge values see: Orders of magnitude (charge)

Electric current (current of charge)

Voltage (electric potential difference)

Electric resistance, conductance, and conductivity

Electric capacitance

Electric inductance

Energy carried by electricity or electric energy

Power carried by electricity (current of energy)

Electric field (negative gradient of electric potential, voltage per length)

Magnetic field

See also the relevant section in the article about the magnetic B field|magnetic field].
For the ranges of magnetic field see: Orders of magnitude (magnetic field)

Combination instruments

  • Multimeter, combines the functions of ammeter, voltmeter, and ohmmeter as a minimum.
  • LCR meter, combines the functions of ohmmeter, capacitance meter, and inductance meter. Also called component bridge due to the bridge circuit method of measurement.

Thermodynamics

Temperature-related considerations dominate thermodynamics. There are two distinct thermal properties: A thermal potential — the temperature. For example: A glowing coal has a different thermal quality than a non-glowing one.
And a substance-like property, — the entropy; for example: One glowing coal won't heat a pot of water, but a hundred will.
Energy in thermodynamics is calculated by multiplying the thermal potential by the amount of entropy found at that potential: temperature times entropy.
Entropy can be created by friction but not annihilated.

Amount of substance

Temperature

Imaging technology

See also Temperature measurement and :Category:Thermometers. More technically related may be seen thermal analysis methods in materials science.
For the ranges of temperature-values see: Orders of magnitude (temperature)

Energy carried by entropy or thermal energy

This includes thermal mass or temperature coefficient of energy, reaction energy, heat flow,...
Calorimeters are called passive if gauged to measure emerging energy carried by entropy, for example from chemical reactions. Calorimeters are called active or heated if they heat the sample, or reformulated: if they are gauged to fill the sample with a defined amount of entropy.

Entropy

Entropy is accessible indirectly by measurement of energy and temperature.

Entropy transfer

Phase change calorimeter's energy value divided by absolute temperature give the entropy exchanged. Phase changes produce no entropy and therefore offer themselves as an entropy measurement concept. Thus entropy values occur indirectly by processing energy measurements at defined temperatures, without producing entropy.

Entropy content

The given sample is cooled down to absolute zero. At absolute zero temperature any sample is assumed to contain no entropy. Then the following two active calorimeter types can be used to fill the sample with entropy until the desired temperature has been reached:

Entropy production

Processes transferring energy from a non-thermal carrier to heat as a carrier do produce entropy.
Either the produced entropy or heat are measured or the transferred energy of the non-thermal carrier may be measured.
  • calorimeter
*
Entropy lowering its temperature—without losing energy—produces entropy.
  • calorimeter

Temperature coefficient of energy or "heat capacity"

Concerning a given sample, a proportionality factor relating temperature change and energy carried by heat. If the sample is a gas, then this coefficient depends significantly on being measured at constant volume or at constant pressure.

Specific temperature coefficient of energy or "specific heat capacity"

The temperature coefficient of energy divided by a substance-like quantity describing the sample. Usually calculated from measurements by a division or could be measured directly using a unit amount of that sample.
For the ranges of specific heat capacities see: Orders of magnitude (specific heat capacity)

Coefficient of thermal expansion

Melting temperature

Boiling temperature

See also Thermal analysis, Heat.

More on continuum mechanics

This includes mostly instruments which measure macroscopic properties of matter: In the fields of solid-state physics; in condensed matter physics which considers solids, liquids, and in-betweens exhibiting for example viscoelastic behavior; and furthermore, in fluid mechanics, where liquids, gases, plasmas, and in-betweens like supercritical fluids are studied.

Density

This refers to particle density of fluids and compact solids like crystals, in contrast to bulk density of grainy or porous solids.
For the ranges of density-values see: Orders of magnitude (density)

Hardness

Shape and surface of a solid

Deformation

Elasticity

Plasticity

Tensile strength, ductility, or malleability

Granularity

Viscosity

Optical activity

Surface tension

Imaging technology

  • Tomograph, device and method for non-destructive analysis of multiple measurements done on a geometric object, for producing 2- or 3-dimensional images, representing the inner structure of that geometric object.
  • Wind tunnel
This section and the following sections include instruments from the wide field of :Category:Materials science, materials science.

More on electric properties of condensed matter or gas

Permittivity, relative static permittivity, (dielectric constant), or electric susceptibility

Such measurements also allow to access values of molecular dipoles.

Magnetic susceptibility or magnetization

For other methods see the section in the article about magnetic susceptibility.
See also :Category:Electric and magnetic fields in matter

Substance potential, chemical potential, or molar Gibbs energy

Phase conversions like changes of aggregate state, chemical reactions or nuclear reactions transmuting substances, from reactants into products, or diffusion through membranes have an overall energy balance. Especially at constant pressure and constant temperature, molar energy balances define the notion of a substance potential or chemical potential or molar Gibbs energy, which gives the energetic information about whether the process is possible or not - in a closed system.
Energy balances that include entropy consist of two parts: A balance that accounts for the changed entropy content of the substances, and another one that accounts for the energy freed or taken by that reaction itself, the Gibbs energy change. The sum of reaction energy and energy associated to the change of entropy content is also called enthalpy. Often the whole enthalpy is carried by entropy and thus measurable calorimetrically.
For standard conditions in chemical reactions either molar entropy content and molar Gibbs energy with respect to some chosen zero point are tabulated. Or molar entropy content and molar enthalpy with respect to some chosen zero are tabulated.
The substance potential of a redox reaction is usually determined electrochemically current-free using reversible cells.
Other values may be determined indirectly by calorimetry. Also by analyzing phase-diagrams.

Sub-microstructural properties of condensed matter or gas

Crystal structure

Imaging

Sound, compression waves in matter

Microphones in general, sometimes their sensitivity is increased by the reflection- and concentration principle realized in acoustic mirrors.

Sound pressure

Light and radiation without a rest mass, non-ionizing

See also :Category:Optical devices

Photon polarization

Pressure (current density of linear momentum)

Radiant flux

The measure of the total power of light emitted.

Radiation

Cathode rays

Atom polarization and electron polarization

Ionizing radiation

Ionizing radiation includes rays of "particles" as well as rays of "waves". Especially X-rays and gamma rays transfer enough energy in non-thermal, collision processes to separate electron from an atom.

Particle and ray flux

Identification and content

This could include chemical substances, rays of any kind, elementary particles, and quasiparticles. Many measurement devices outside this section may be used or at least become part of an identification process.
For identification and content concerning chemical substances, see also Analytical chemistry, List of chemical analysis methods, and List of materials analysis methods.

Content in mixtures, substance identification

pH: Concentration of protons in a solution

Humidity

Human senses and human body

Sight

Brightness: photometry

Photometry is the measurement of light in terms of its perceived brightness to the human eye. Photometric quantities derive from analogous radiometric quantities by weighting the contribution of each wavelength by a luminosity function that models the eye's spectral sensitivity. For the ranges of possible values, see the orders of magnitude in:
illuminance,
luminance, and
luminous flux.

Color: colorimetry

Radar brightness: radiometry

Synthetic Aperture Radar (SAR) instruments measure radar brightness, Radar Cross Section (RCS), which is a function of the reflectivity and moisture of imaged objects at wavelengths which are too long to be perceived by the human eye. Black pixels mean no reflectivity, white pixels mean high reflectivity. Colored pixels can be obtained by combining three gray-scaled images which usually interpret the polarization of electromagnetic waves. The combination R-G-B = HH-HV-VV combines radar images of waves sent and received horizontally, sent horizontally and received vertically and sent and received vertically. The calibration of such instruments is done by imaging objects whose radar brightness is known.

Hearing

Loudness in phon

Smell

Temperature (sense and body)

Body temperature or core temperature

Circulatory system

Blood-related parameters are listed in a blood test.

Respiratory system

[Concentration] or [partial pressure] of [carbon dioxide] in the respiratory gases

Nervous system

Musculoskeletal system

Power, work of muscles

Metabolic system

Medical imaging

See also: :Category:Physiological instruments and :Category:Medical testing equipment.

Meteorology

See also :Category:Meteorological instrumentation and equipment.

Navigation

See also :Category:Navigational equipment and :Category:Navigation.
See also Surveying instruments.

Astronomy

See also Astronomical instruments and :Category:Astronomical observatories.

Military

Some instruments, such as telescopes and sea navigation instruments, have had military applications for many centuries. However, the role of instruments in military affairs rose exponentially with the development of technology via applied science, which began in the mid-19th century and has continued through the present day. Military instruments as a class draw on most of the categories of instrument described throughout this article, such as navigation, astronomy, optics, and imaging, and the kinetics of moving objects. Common abstract themes that unite military instruments are seeing into the distance, seeing in the dark, knowing an object's geographic location, and knowing and controlling a moving object's path and destination. Special features of these instruments may include ease of use, speed, reliability, and accuracy.

Uncategorized, specialized, or generalized application