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The fundamental structure of the metric system is characterized by its reliance on decimal (base-10) relationships among units and the systematic use of prefixes to denote multiplicative factors.
Answer: True
The metric system is indeed fundamentally based on decimal (base-10) relationships between units, employing prefixes to denote multiplicative factors, which contributes to its coherence and ease of use.
The modern metric system is designated as the International System of Units (SI), which establishes conventions for prefixes and defines seven fundamental base units.
Answer: True
The modern metric system is officially known as the International System of Units (SI). It standardizes rules for prefixes and defines seven base units for fundamental physical quantities.
The convention for deriving metric prefixes dictates that those denoting multiples of ten are typically derived from Greek roots, while those denoting sub-multiples are derived from Latin roots.
Answer: True
There is a general convention where prefixes for multiples (e.g., kilo-, mega-) are derived from Greek, and prefixes for sub-multiples (e.g., centi-, milli-) are derived from Latin. However, this convention has exceptions and has evolved over time.
When applying prefixes to derived units of area or volume, such as square metres or cubic metres, the exponentiation applies to both the unit and its prefix.
Answer: True
For derived units like area (m²) or volume (m³), when a prefix is used, the exponent applies to the entire prefixed unit. For example, 1 mm² is equal to (1 mm)², which is (0.001 m)², resulting in 10⁻⁶ m².
The metric system's ease of use is attributed to its coherent structure and decimal ratios.
Answer: True
The systematic decimal nature, coherent structure, and standardized prefixes are key factors contributing to the metric system's widespread adoption and ease of application.
Coherence in a unit system signifies that derived units are directly related to base units without the need for conversion factors.
Answer: True
A coherent system of units ensures that derived units are formed directly from base units through multiplication and division, without introducing arbitrary numerical factors, simplifying physical equations.
While 'yotta-' (10^24) and 'yocto-' (10^-24) are SI prefixes, they are not the most recent extensions to the system.
Answer: True
As of 2022, the SI system introduced 'quetta-' (10^30) and 'quecto-' (10^-30) as the most recent extensions to the prefix nomenclature.
What is the fundamental characteristic of the metric system regarding quantities?
Answer: It is a decimal-based system using standardized base units and multiplicative prefixes.
The metric system's core strength lies in its decimal structure, standardized base units, and the systematic application of prefixes to denote multiples and sub-multiples.
What is the general convention for the origin of metric prefixes for positive powers of ten (multiples)?
Answer: Derived from Greek words.
Prefixes denoting multiples of ten in the metric system are generally derived from Greek words (e.g., 'kilo-' from 'khilioi' meaning thousand).
How is the exponentiation applied when using prefixes with derived units of area, like square metres?
Answer: The exponent applies to both the unit and the prefix (e.g., (mm)²).
When a prefix is applied to a derived unit involving powers, such as area (m²) or volume (m³), the exponent applies to the entire prefixed unit. For example, 1 mm² = (1 mm)² = (10⁻³ m)² = 10⁻⁶ m².
What does 'coherence' mean in the context of a system of units?
Answer: Derived units are directly related to base units without conversion factors.
Coherence in a unit system means that derived units are formed from base units by multiplication and division alone, without the introduction of numerical factors, thus simplifying equations.
Which pair represents the most recent SI prefixes introduced as of 2022?
Answer: Quetta- (10^30) and Qecto- (10^-30)
The most recent SI prefixes, adopted in November 2022, are 'quetta-' for 10^30 and 'quecto-' for 10^-30. 'Ronna-' and 'ronto-' were also introduced at the same time.
The seven base units of the SI system include the metre for length, kilogram for mass, and second for time.
Answer: True
The metre (m) for length, kilogram (kg) for mass, and second (s) for time are indeed among the seven base units defined by the International System of Units (SI).
SI derived units are formed by combining base units through multiplication and division, not by addition.
Answer: True
SI derived units are constructed by combining base units through multiplication, division, or both. For example, the newton (N), a unit of force, is defined as kg⋅m/s², illustrating this principle.
A 60-watt incandescent light bulb radiating uniformly exhibits a luminous intensity of approximately 64 candelas.
Answer: True
The candela (cd) is the SI unit for luminous intensity. A standard 60-watt incandescent bulb, when radiating light uniformly, produces approximately 64 candelas.
The mass of one mole of a substance, when expressed in grams, is numerically equivalent to its molecular mass.
Answer: True
This statement reflects the concept of molar mass: one mole of any substance contains Avogadro's number of particles and has a mass in grams numerically equal to its atomic or molecular mass.
The density of a gas relative to air can be approximated by dividing the gas's molecular mass by the approximate average molecular mass of air, which is 29.
Answer: True
This approximation is valid because the average molecular mass of air is approximately 29 g/mol. Thus, a gas with a molecular mass greater than 29 will be denser than air.
Which of the following is NOT one of the seven base units of the International System of Units (SI)?
Answer: Joule (J) for energy
The Joule (J) is an SI derived unit used for energy, defined as the work done when a force of one newton is applied over one metre (N⋅m). The seven SI base units are the metre, kilogram, second, ampere, kelvin, mole, and candela.
How are SI derived units formed?
Answer: By combining base units through multiplication and division.
SI derived units are formed by combining the seven base units through algebraic relations, typically involving multiplication and division, to express quantities like force, energy, or power.
What does the mass of one mole of a substance, expressed in grams, correspond to?
Answer: Its molecular mass.
The molar mass of a substance, defined as the mass of one mole of that substance, is numerically equivalent to its atomic or molecular mass expressed in grams per mole (g/mol).
How can the approximate density of a gas relative to air be estimated?
Answer: By dividing the gas's molecular mass by the approximate average molecular mass of air (29).
The relative density of a gas compared to air can be approximated by dividing the gas's molecular mass by the average molecular mass of air, which is approximately 29 g/mol.
Which of the following is an example of an SI derived unit mentioned in the source?
Answer: Newton (N)
The metre, ampere, and second are SI base units. The Newton (N), used to measure force, is an example of an SI derived unit, defined as kg⋅m/s².
The metric system's extensibility is demonstrated by the ability to introduce new units, such as the 'katal' for what purpose?
Answer: Catalytic activity
The introduction of units like the 'katal' for catalytic activity exemplifies the SI system's capacity for extension and adaptation to new scientific fields and measurement needs.
The current SI system is a direct continuation and evolution of the older metre-kilogram-second (MKS) system.
Answer: True
The SI system evolved from the metre-kilogram-second (MKS) system, refining and standardizing definitions, particularly for electrical units, and establishing a more comprehensive framework.
Historical variants of the metric system include the centimetre-gram-second (CGS) and metre-tonne-second (MTS) systems, as well as gravitational metric systems.
Answer: True
The history of the metric system includes various forms such as the CGS (centimetre-gram-second), MTS (metre-tonne-second), and gravitational metric systems, each with different base units or conventions.
The centimetre-gram-second (CGS) system, unlike SI, did not achieve full coherence due to having separate units for mechanical and thermal energy.
Answer: True
The CGS system faced challenges with coherence, particularly concerning energy, as it used distinct units for mechanical energy (erg) and thermal energy (calorie), whereas SI employs a single coherent unit, the joule.
The centimetre-gram-second (CGS) system utilized the erg as the unit for force and the dyne as the unit for energy.
Answer: False
In the CGS system, the dyne is the unit of force, and the erg is the unit of energy. The statement incorrectly reverses these.
The CGS system's handling of electrical units was complicated by the existence of separate electrostatic and electromagnetic unit systems.
Answer: True
The CGS system included distinct sets of units for electrostatic phenomena (cgs-esu) and electromagnetic phenomena (cgs-emu), which often led to cumbersome conversions and practical difficulties.
In 1893, the 'international' definitions for the ampere and ohm were established based on the metre, kilogram, and second.
Answer: True
The 1893 International Electrical Congress defined the 'international' ampere and ohm using the mechanical units of the metre, kilogram, and second, marking a significant step towards a coherent system including electrical units.
Giovanni Giorgi proposed incorporating an electrical unit as a fourth base unit into the metric system, which influenced the development of systems like MKSA.
Answer: True
Giovanni Giorgi's proposal in the early 20th century to add an electrical unit (ampere) as a fourth base unit to the metric system (leading to the MKSA system) was pivotal in unifying mechanics and electromagnetism.
The SI system was officially promulgated in 1960, at which time the metre was redefined based on the speed of light.
Answer: False
While the SI system was promulgated in 1960, the metre was redefined based on the wavelength of light emitted by krypton-86 atoms at that time. The definition based on the speed of light was adopted later, in 1983.
The metre-tonne-second (MTS) system was developed for industrial applications and was adopted by the Soviet Union.
Answer: True
The metre-tonne-second (MTS) system was indeed developed in France for industrial use and was officially adopted in the Soviet Union from 1933 until 1955.
The SI system evolved from which older metric system?
Answer: Metre-kilogram-second (MKS)
The International System of Units (SI) is largely based on the metre-kilogram-second (MKS) system, which provided a foundation for defining units in mechanics and later incorporated electrical units.
How did the CGS system differ from SI regarding energy units?
Answer: CGS had separate units for mechanical (erg) and thermal (calorie) energy, while SI uses a single coherent unit (joule).
The CGS system lacked coherence in energy units, employing the erg for mechanical energy and the calorie for thermal energy. SI resolved this by defining the joule as a single, coherent unit for all forms of energy.
The centimetre-gram-second (CGS) system primarily used which unit for force?
Answer: Dyne
In the CGS system, the unit of force is the dyne, defined as the force required to accelerate a mass of one gram by one centimetre per second squared (g⋅cm/s²).
What challenge did the CGS system face regarding electrical and magnetic units?
Answer: It had separate, often cumbersome, electrostatic and electromagnetic units.
The CGS system was characterized by having two distinct sets of units for electricity and magnetism: electrostatic units (esu) and electromagnetic units (emu), which often required complex conversion factors.
Giovanni Giorgi's proposal involved adding which type of unit as a fourth base unit to the metric system?
Answer: An electrical unit
Giovanni Giorgi proposed incorporating an electrical unit, specifically the ampere, as a fourth base unit to the existing metre-kilogram-second (MKS) system, leading to the development of the MKSA system.
When the SI system was promulgated in 1960, the metre was redefined based on what?
Answer: The wavelength of light from krypton-86.
The metre was redefined in 1960, coinciding with the promulgation of the SI system, based on the wavelength of the orange-red emission line of krypton-86.
Which historical metric system was developed in France for industrial use and later adopted by the Soviet Union?
Answer: MTS (Metre-tonne-second)
The metre-tonne-second (MTS) system was developed in France for industrial applications and was adopted for use in the Soviet Union from 1933 to 1955.
What was a key change in the definition of SI base units after the 1960 promulgation?
Answer: The metre was redefined based on the wavelength of krypton-86.
Upon the promulgation of the SI system in 1960, the definition of the metre was updated to be based on the wavelength of the spectral line of krypton-86.
Which historical system was the first coherent metric system, promoted by scientists like Maxwell and Kelvin?
Answer: CGS
The centimetre-gram-second (CGS) system, developed in the 1860s and championed by prominent scientists like James Clerk Maxwell and Lord Kelvin, is recognized as the first coherent metric system.
The current SI system defines base units using fundamental physical constants to ensure greater accuracy and stability, rather than relying on physical artefacts.
Answer: True
A significant advancement in the SI system is the redefinition of its base units based on invariant physical constants, such as the speed of light and the Planck constant, ensuring universal and stable definitions.
The kilogram was historically defined by a platinum-iridium artefact, but this definition has been replaced by one based on the Planck constant.
Answer: True
The definition of the kilogram transitioned from the physical International Prototype of the Kilogram to a definition based on the exact value of the Planck constant, enhancing its stability and universality.
The term '*mise en pratique*' refers to the practical methods and procedures used to realize each SI base unit.
Answer: True
The '*mise en pratique*' provides the detailed practical guidance necessary for laboratories to realize and measure each SI base unit, ensuring consistency and reproducibility.
The SI system's base units are now defined using invariant physical constants, ensuring greater accuracy and stability.
Answer: True
The modern definitions of SI base units are anchored in fundamental physical constants, providing a stable, universally accessible, and highly accurate basis for measurement.
What principle guides the current definition of SI base units?
Answer: Fundamental physical constants.
The modern SI framework defines its base units based on fundamental physical constants, ensuring greater precision, stability, and universality compared to earlier definitions tied to physical prototypes or specific measurements.
Which fundamental constant is now used to define the kilogram?
Answer: The Planck constant
The kilogram is now defined by the exact numerical value of the Planck constant (h), linking the unit of mass to a fundamental constant of quantum mechanics.
What is the purpose of the *mise en pratique* within the SI system?
Answer: To offer practical guidance for realizing each SI base unit.
The '*mise en pratique*' consists of the practical procedures and experimental methods that allow laboratories worldwide to realize and measure each SI base unit, ensuring consistency and traceability.
Why did the definition of the kilogram change from a physical artefact?
Answer: The artefact showed signs of drift, impacting stability.
The physical artefact defining the kilogram exhibited minute changes over time (drift), compromising the long-term stability and accuracy required for a fundamental unit. Redefining it based on the Planck constant resolved this issue.
Units such as the litre (L) and the degree (°), while not strictly SI base units, are accepted for use within the SI framework.
Answer: True
Units like the litre (L) and the degree (°), along with minutes and hours for time, are accepted for use with the SI system, even though they are not among the seven SI base units themselves.
Rationalisation, as proposed by Oliver Heaviside, aimed to simplify equations by removing factors like 1/(4π) from electromagnetic units.
Answer: True
Oliver Heaviside advocated for 'rationalisation' in electromagnetic units to eliminate the factor of 1/(4π) that appeared frequently in Maxwell's equations, thereby simplifying the formulation.
While the second is the SI base unit for time, its common multiples like the minute and hour are based on sexagesimal (base-60) multipliers, not decimal.
Answer: True
Despite the SI system's decimal foundation, common units of time such as minutes and hours retain their historical sexagesimal (base-60) relationships, rather than adopting decimal multipliers.
One litre of cold water possesses a mass that is approximately equivalent to one kilogram.
Answer: True
The relationship between volume and mass for water is notably convenient: one litre of cold water has a mass very close to one kilogram.
For water, one millilitre occupies the same volume as one cubic centimetre and has a mass of one gram.
Answer: True
The metric system provides a simple relationship for water: one millilitre (mL) is equivalent to one cubic centimetre (cm³), and one millilitre of water has a mass of approximately one gram (g).
A temperature difference of one degree Celsius is equivalent to a difference of one Kelvin, although the scales have different zero points.
Answer: True
The magnitude of a temperature difference is the same on both the Celsius and Kelvin scales; a change of 1°C corresponds to a change of 1 K. However, the Kelvin scale's zero point (absolute zero) is at -273.15°C.
Gravitational metric systems, which utilize units like the kilogram-force, are not considered part of the International System of Units (SI).
Answer: True
Gravitational metric systems, characterized by units such as the kilogram-force (kgf), are distinct from and not included within the framework of the International System of Units (SI).
Which unit, accepted for use with SI, is based on sexagesimal (base-60) multipliers rather than decimal?
Answer: Degree (°)
Units of time (minute, hour) and angle (degree, arcminute, arcsecond) are accepted for use with SI but retain their historical sexagesimal (base-60) structure, contrasting with the SI's decimal foundation.
Oliver Heaviside proposed 'rationalisation' to simplify physical equations by removing which type of factor?
Answer: Factors of 1/(4π)
Heaviside's rationalisation aimed to remove the factor of 1/(4π) from equations involving electromagnetism, particularly those derived from Coulomb's law and Gauss's law, to simplify their appearance.
While the second is the SI base unit for time, what is the multiplier base for common units like the minute and hour?
Answer: Sexagesimal (base-60)
Units such as minutes and hours, commonly used for time, are derived from ancient systems that employ sexagesimal (base-60) multipliers, despite the SI system's decimal foundation.
What simple relationship exists between volume and mass for water concerning millilitres and grams?
Answer: 1 millilitre of water has a mass of 1 gram.
Water exhibits a convenient property where one millilitre (which is equivalent to one cubic centimetre) has a mass of approximately one gram, simplifying many calculations.
How does one convert a temperature from Celsius to Kelvin?
Answer: Add 273 to the Celsius value.
To convert a temperature from degrees Celsius (°C) to Kelvin (K), one adds approximately 273.15 to the Celsius value (K = °C + 273.15).
What is the relationship between the Celsius and Kelvin temperature scales regarding differences?
Answer: A difference of 1°C is equal to a difference of 1 K.
The size of one degree Celsius is identical to the size of one Kelvin. Therefore, a temperature difference of 1°C is equivalent to a temperature difference of 1 K.
Gravitational metric systems are characterized by the use of units like the kilogram-force, but are they part of the SI?
Answer: No, they are not considered part of the SI.
Gravitational metric systems, which often employ units like the kilogram-force (kgf), are not officially recognized or included within the International System of Units (SI).
The SI system has achieved widespread global adoption, although the United States remains a notable exception in its full implementation.
Answer: True
The International System of Units (SI) is the predominant system of measurement globally. The United States is recognized as a primary example of a country that has not fully adopted the metric system for general use.
The term 'metrication' specifically refers to the process of adopting the metric system.
Answer: True
Metrication is the established term used to describe the process by which a country or industry transitions to using the metric system of measurement.
The original definition of the metre was based on a fraction of the Earth's circumference.
Answer: True
The initial definition of the metre, established during the French Revolution, was set as one ten-millionth of the distance from the North Pole to the Equator along the meridian passing through Paris.
Gabriel Mouton proposed a decimal system of measurement based on Earth's circumference in the 17th century, predating the French Revolution's metric system.
Answer: True
Gabriel Mouton, a vicar in Lyons, France, proposed a decimal system around 1665-1670, suggesting a unit of length based on one minute of arc of the Earth's circumference.
Antoine and Marie-Anne Lavoisier developed an early metric system during the French Revolution, basing units on Earth's dimensions and water's mass.
Answer: True
The influential scientists Antoine and Marie-Anne Lavoisier were instrumental in developing an early version of the metric system during the French Revolution, grounding units in natural phenomena like the Earth's dimensions and the properties of water.
The primary motivation for reforming French weights and measures during the Revolution was to align them with British imperial standards.
Answer: False
The principal driver for reforming French weights and measures was the need to replace the chaotic and inconsistent array of local systems then in use, aiming for a unified, rational system, not alignment with British standards.
The goal of the French National Assembly in 1790 was to create a single, standardized system based on natural units.
Answer: True
In 1790, the French National Assembly resolved to establish a new system of weights and measures that was uniform, based on natural and invariable standards, and intended for universal adoption.
Charles Maurice de Talleyrand-Périgord was among the figures who proposed the metric system to the French National Assembly.
Answer: True
Charles Maurice de Talleyrand-Périgord played a role in advocating for the adoption of a new, unified system of weights and measures, presenting proposals to the French National Assembly.
Which country is identified as a notable outlier in its resistance to full adoption of the metric system?
Answer: United States
The United States is widely recognized as a country that has not fully adopted the metric system for widespread use in commerce and daily life, despite its use in scientific and technical fields.
What was the original definition of the metre?
Answer: One ten-millionth of the distance from the North Pole to the Equator through Paris.
The initial definition of the metre, established during the French Revolution, was based on the Earth's dimensions, specifically one ten-millionth of the distance from the North Pole to the Equator along a meridian.
Who is credited with suggesting a decimal system of measurement based on Earth's circumference around 1670?
Answer: Gabriel Mouton
Gabriel Mouton, a French abbé, proposed a decimal system of measurement in the late 17th century, suggesting a unit of length derived from the Earth's circumference.
What was the primary motivation behind France's reform of weights and measures during the French Revolution?
Answer: To replace the numerous and varied local systems in use.
The French Revolution sought to unify the nation by replacing the multitude of inconsistent and localized weights and measures with a single, rational, and universally applicable system.