ফ্লাক্স: সংশোধিত সংস্করণের মধ্যে পার্থক্য
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Wiki Nahid NHB (আলাপ)-এর সম্পাদিত 4932681 নম্বর সংশোধনটি বাতিল করা হয়েছে ট্যাগ: পূর্বাবস্থায় ফেরত মোবাইল সম্পাদনা মোবাইল ওয়েব সম্পাদনা উচ্চতর মোবাইল সম্পাদনা |
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১১ নং লাইন:
==পরিভাষা ==
ফ্লাক্স শব্দটি ''লাতিন'' শব্দ ''ফ্লাক্সাস ''এবং ''ফ্লুইর'' থেকে এসেছে : এদের অর্থ যথাক্রমে 'প্রবাহিত' এবং 'প্রবাহিত হওয়া'। <ref>{{Cite book | title=An Etymological Dictionary of Modern English | first=Ernest | last=Weekley | publisher=Courier Dover Publications | year=1967 | isbn=0-486-21873-2 | page=581 }}</ref> [[আইজ্যাক নিউটন ]] ''[[ফ্লাক্সিয়ন এর পদ্ধতিসমূহ |ফ্লাক্সিয়ন ]]'' নামটি প্রথম [[ডিফারেন্সিয়াল ক্যালকুলাস ]] এ ব্যবহার করে।
The concept of heat flux was a key contribution of [[Joseph Fourier]], in the analysis of heat transfer phenomena.<ref>{{cite book |last1=Herivel |first1=John |title=Joseph Fourier : the man and the physicist |date=1975 |publisher=Clarendon Press |location=Oxford |isbn=0198581491 |pages=181–191}}</ref> His seminal treatise ''Théorie analytique de la chaleur'' (''The Analytical Theory of Heat''),<ref>{{Cite book | last = Fourier | first = Joseph | title = Théorie analytique de la chaleur | publisher = Firmin Didot Père et Fils | year = 1822 | location = Paris | language = fr | url=https://archive.org/details/bub_gb_TDQJAAAAIAAJ | oclc=2688081 }}</ref> defines ''fluxion'' as a central quantity and proceeds to derive the now well-known expressions of flux in terms of temperature differences across a slab, and then more generally in terms of temperature gradients or differentials of temperature, across other geometries. One could argue, based on the work of [[James Clerk Maxwell]],<ref name = Maxwell/> that the transport definition precedes the [[Magnetic flux|definition of flux used in electromagnetism]]. The specific quote from Maxwell is:
{{quote|In the case of fluxes, we have to take the integral, over a surface, of the flux through every element of the surface. The result of this operation is called the [[surface integral]] of the flux. It represents the quantity which passes through the surface. |James Clerk Maxwell}}
According to the transport definition, flux may be a single vector, or it may be a vector field / function of position. In the latter case flux can readily be integrated over a surface. By contrast, according to the electromagnetism definition, flux ''is'' the integral over a surface; it makes no sense to integrate a second-definition flux for one would be integrating over a surface twice. Thus, Maxwell's quote only makes sense if "flux" is being used according to the transport definition (and furthermore is a vector field rather than single vector). This is ironic because Maxwell was one of the major developers of what we now call "electric flux" and "magnetic flux" according to the electromagnetism definition. Their names in accordance with the quote (and transport definition) would be "surface integral of electric flux" and "surface integral of magnetic flux", in which case "electric flux" would instead be defined as "electric field" and "magnetic flux" defined as "magnetic field". This implies that Maxwell conceived of these fields as flows/fluxes of some sort.
Given a flux according to the electromagnetism definition, the corresponding '''flux density''', if that term is used, refers to its derivative along the surface that was integrated. By the [[Fundamental theorem of calculus]], the corresponding '''flux density''' is a flux according to the transport definition. Given a '''current''' such as electric current—charge per time, '''current density''' would also be a flux according to the transport definition—charge per time per area. Due to the conflicting definitions of ''flux'', and the interchangeability of ''flux'', ''flow'', and ''current'' in nontechnical English, all of the terms used in this paragraph are sometimes used interchangeably and ambiguously. Concrete fluxes in the rest of this article will be used in accordance to their broad acceptance in the literature, regardless of which definition of flux the term corresponds to.
==তথ্যসূত্র==
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