किलोग्राम

विकिपीडिया, एक मुक्त ज्ञानकोष से

उपरोक्त दिखाया गया चित्र्, अन्तराष्ट्रीय मूलरूप किलोग्राम का एक कम्प्यूटर निर्मित चित्र है। इसके समीप रखा एक इंच का पैमाना है। इस भार को IPK भी कहते हैं. यह प्लैटिनम-इर्रीडियम मिश्रण का बना है, और BIPM , सेवर्स, फ़्रांस में रखा है.

किलोग्राम (चिन्ह: kg) भार की SI इकाई है. एक किलोग्राम की परिभाषानुसार, {{उक्ति|यह अन्तर्राष्ट्रीय मूलरूप किलोग्राम, IPK, ^[१] (IPK; जो अपने फ़्रेंच नाम ली ग्रैंड K से जाना जाता है), के भार के बराबर है, जो कि एक लीटर जल के भार के एकदम बराबर है. यह इकलौती SI इकाई है, जिसका उपसर्ग किलो उसके नाम का भाग है.

दैनिक प्रयोग में हम किलोग्राम को वस्तुओं के भार के रूप में ही जानते हैं, परंतु वह भार ना होकर द्रव्यमान का माप ही है. किसी वस्तु का भार उस पर्लगी गुरुत्वाकर्षण बल का माप होता है, और्वह न्यूटन में मापा जाता है.^[२].

SI इकाई प्रणाली में कई इकाइयाँ किलोग्राम के सापेक्ष ही परिभाषित हैं, अतएव इसकी स्थिरता महत्वपूर्ण है. जब IPK को समय के साथ बदलता पाया गया, तब CIPM ने 2005 में यह तय किया, कि किलोग्राम को प्रकॄति के मूल स्थिरांकों में परिभशःइत किया जये. ^[३]

[संपादित करें] SI गुणक

क्योंकि SI उपसर्ग किसी मापन इकाई के नाम या चिन्ह के साथ सीधे नहीं जोड़े जा सकते हैं, इसलिये यह उपसग ग्राम के साथ ही जोड़े जाते हैं, नाकि किलोग्राम के साथ, जिसके साथ पहले ही किलो उपसर्ग लगा है.^[४] उदा० एक किलोग्राम का दस लाखवाँ भाग है 1 mg (एक मिलिग्राम), नाकि 1 µkg (एक माइक्रोकिलोग्राम).

(mu) in the symbol of microgram is typographically unavailable, it is occasionally—although not properly—replaced by Latin lowercase “u”.

• The microgram is often abbreviated “mcg”, particularly in pharmaceutical and nutritional supplement labeling, to avoid confusion since the “µ” prefix is not well recognized outside of technical disciplines.^[६] Note however, that the abbreviation “mcg”, is also the symbol for an obsolete CGS unit of measure known as the “millicentigram”, which is equal to 10 µg.
• The unit name “megagram” is rarely used, and even then, typically only in technical fields in contexts where especially rigorous consistency with the units of measure is desired. For most purposes, the unit “tonne” is instead used. The tonne and its symbol, t, were adopted by the CIPM in 1879. It is a non-SI unit accepted by the BIPM for use with the SI. In English speaking countries it is usually called “metric ton”.^[७] Note also that the unit name “megatonne” or “megaton” (Mt) is often used in general-interest literature on greenhouse gas emissions whereas the equivalent value in scientific papers on the subject is often the “teragram” (Tg). -->

[संपादित करें] शब्द-संग्रह

• Abstracted: Isolated and its effect changed in form, often simplified or made more accessible in the process.
• Artifact: A human-made object used as a comparative standard in the measurement of a physical quantity.
• Check standard:

1. A standard body’s backup replica of the International Prototype Kilogram (IPK).
2. A secondary kilogram mass standard used as a stand-in for the primary standard during routine calibrations.

• Definition: A formal, specific, and exact specification.
• Delineation: The physical means used to mark a boundary or express the magnitude of an entity.
• Disseminate: To widely distribute the magnitude of a unit of measure, typically via replicas and transfer standards.
• IPK: Abbreviation of “International Prototype Kilogram” (CG image), the artifact which has a mass defined as precisely one kilogram.
• Magnitude: The extent or numeric value of a property
• National prototype: A replica of the IPK possessed by a nation.
• Practical realization: An artifact or readily reproducible apparatus to conveniently delineate the magnitude of a unit of measure.
• Primary national standard:

1. A replica of the IPK possessed by a nation
2. The least used replica of the IPK when a nation possesses more than one.

• Prototype:

1. A human-made object that serves as the defining comparative standard in the measurement of a physical quantity.
2. A human-made object that serves as the comparative standard in the measurement of a physical quantity.
3. The IPK and any of its replicas

• Replica: An official copy of the IPK.
• Sister copy: One of six official copies of the IPK that are stored in the same safe as the IPK and are used as check standards by the BIPM.
• Transfer standard: An artifact or apparatus that reproduces the magnitude of a unit of measure in a different, usually more practical, form.

[संपादित करें] देखें

[संपादित करें] टिप्पणी

1. ↑ BIMP: Resolution of the 1st CGPM (1889) 
2. ↑ NIST: Converting Measurements to Metric--NIST FAQs; the U.K.’s National Weights & Measures Laboratory: Metric Conversions; and NIST: Fed-Std-376B, Preferred Metric Units for General Use By the Federal Government, Section 5.2.1 Mass (weight) (294 KB PDF, here). 
3. ↑ Proceedings of the 94th meeting (October 2005) of the International Committee for Weights and Measures, (1.1 MB zip file, here) 
4. ↑ BIPM: SI Brochure: Section 3.2, The kilogram 
5. ↑ Criterion: A combined total of at least 250,000 Google hits on both the U.S. spelling (‑gram) and the U.K./International spelling (‑gramme). 
6. ↑ The practice of using the abbreviation “mcg” rather than the SI symbol “µg” was formally mandated for medical practitioners in 2004 by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) in their “Do Not Use” List: Abbreviations, Acronyms, and Symbols because hand-written expressions of “µg” can be confused with “mg”, resulting in a thousand-fold overdosing. The mandate was also adopted by the Institute for Safe Medication Practices. 
7. ↑ BIPM: SI Brochure: Section 4.1, Non-SI units accepted for use with the SI, and units based on fundamental constants: Table 6 

[संपादित करें] बाहरी कड़ियां

External images
	BIPM: The IPK in three nested bell jars
	NIST: K20, the US National Prototype Kilogram, resting on an egg crate fluorescent light panel
	BIPM: Steam cleaning a 1 kg prototype before a mass comparison
	BIPM: The IPK and its six sister copies in their vault
	The Age: Silicon sphere for the Avogadro Project
	NPL: The NPL’s Watt Balance project
	NIST: The Rueprecht Balance, Austrian-made, precision balance used by the NIST from 1945 until 1960
	BIPM: The FB‑2 flexure-strip balance, the BIPM’s modern precision balance featuring a standard deviation of one ten-billionth of a kilogram (0.1 µg)
	BIPM: Mettler HK1000 balance, featuring 1 µg resolution and a 4 kg maximum mass. Also used by NIST and Sandia National Laboratories’ Primary Standards Laboratory
	Micro-g LaCoste: FG‑5 absolute gravimeter, (diagram), used in national labs to measure gravity to 2 µGal accuracy

• National Institute of Standards and Technology (NIST): NIST Improves Accuracy of ‘Watt Balance’ Method for Defining the Kilogram
• The U.K.’s National Physical Laboratory (NPL): An overview of the problems with an artifact-based kilogram
• NPL: Avogadro Project
• NPL: NPL watt balance
• Metrology in France: Watt balance
• Australian National Measurement Institute: Redefining the kilogram through the Avogadro constant
• International Bureau of Weights and Measures (BIPM): Home page
• NZZ Folio: What a kilogram really weighs
• NPL: What are the differences between mass, weight, force and load?
• BBC: Getting the measure of a kilogram