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Related Concept Videos

Magnetic Flux01:18

Magnetic Flux

4.4K
The magnetic flux measures the number of magnetic field lines passing through a given surface area. The SI unit for magnetic flux is the weber (Wb). Magnetic flux is a scalar quantity. It depends on three factors: the strength of the magnetic field B, the area through which the field lines pass, and the relative orientation of the field with the surface area.
Suppose a surface is divided into elements of area dA. For each element, the component of the magnetic field that is normal to the...
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Flame Photometry: Overview01:02

Flame Photometry: Overview

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Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a sample using a flame as the source of excitation energy. The concept of flame photometry was realized in the early 1860s by Kirchhoff and Bunsen, who discovered that specific elements emit characteristic radiation when excited in flames. The first instrument developed for this purpose was used to measure sodium (Na) in plant ash using a Bunsen...
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Electric Flux01:15

Electric Flux

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The concept of flux describes how much of something goes through a given area. More formally, it is the dot product of a vector field within an area. For a better understanding, consider an open rectangular surface with a small area that is placed in a uniform electric field. The larger the area, the more field lines go through it and, hence, the greater the flux; similarly, the stronger the electric field (represented by a greater density of lines), the greater the flux. On the other hand, if...
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Flame Photometry: Lab01:16

Flame Photometry: Lab

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In a flame photometer, when a solution like potassium chloride is aspirated into the flame, the solvent evaporates, leaving behind dehydrated salt. This salt dissociates into free gaseous atoms in their ground state. Some of these atoms absorb energy from the flame, leading to their excitation. The excited atoms return to the ground state, emitting photons at characteristic wavelengths. Because only electronic transitions are involved, the resulting emission lines are very narrow. The intensity...
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General External Flow Characteristics01:26

General External Flow Characteristics

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The study of external flow is essential for creating structures and objects that interact efficiently and safely with moving fluids, such as air or water. When a body is immersed in a flowing fluid, it experiences two primary forces: drag, which opposes motion along the flow direction, and lift, which acts perpendicular to the flow. The shape, size, and orientation of the object influence these forces.Streamlined and Blunt Bodies in External FlowObjects in fluid flow are classified as...
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Faraday Disk Dynamo01:23

Faraday Disk Dynamo

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A Faraday disk dynamo is a DC generator, producing an emf that is constant in time. It consists of a conducting disk that rotates with a constant angular velocity in the magnetic field, perpendicular to the disk's plane. The rotation of the disk causes a change in magnetic flux, which induces an emf, causing opposite charges to develop on the rim and in the center of the disk. The polarity of the induced emf can be determined by the direction of the magnetic field and the direction of the...
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Related Experiment Video

Updated: Dec 28, 2025

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron
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Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

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On-Disc Observations of Flux Rope Formation Prior to Its Eruption.

A W James1, L M Green1, E Palmerio2

  • 11Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT UK.

Solar Physics
|February 15, 2020
PubMed
Summary
This summary is machine-generated.

Researchers studied the pre-eruption solar corona to understand coronal mass ejections (CMEs). They found evidence of a magnetic flux rope forming via reconnection before a CME, aiding space weather prediction.

Keywords:
Corona: structuresCoronal mass ejections: initiation and propagationMagnetic fields: photosphereRadio emission: active regions

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Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods
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Area of Science:

  • Solar Physics
  • Space Weather Research
  • Astrophysics

Background:

  • Coronal mass ejections (CMEs) are significant solar events with major space weather impacts.
  • Predicting CME occurrence is crucial but challenging due to unclear formation mechanisms.
  • The pre-eruptive state and flux rope presence before CMEs are key unanswered questions.

Purpose of the Study:

  • Investigate the pre-eruptive coronal configuration of an active region that produced an interplanetary CME.
  • Determine if magnetic flux ropes are present before CME onset.
  • Identify the mechanisms responsible for CME formation.

Main Methods:

  • Analysis of extreme-ultraviolet (EUV) data to identify pre-eruptive signatures like sigmoid structures.
  • Utilizing flare ribbons and EUV dimmings to infer flux rope footpoint locations.
  • Examining global magnetic flux distribution and plasma composition.

Main Results:

  • A forward-S sigmoid, indicative of a right-handed flux rope, was observed two hours before the CME.
  • Flux rope footpoints were inferred, suggesting formation via tether-cutting-like reconnection between new and existing magnetic flux.
  • Composition analysis confirmed coronal plasma origin, supporting in-corona formation.

Conclusions:

  • Magnetic flux ropes can form in the corona prior to eruption through tether-cutting reconnection.
  • The observed flux rope remained stable for two hours before erupting as a CME.
  • Understanding these pre-eruptive processes is vital for improving CME prediction and space weather forecasting.