Permeability is the measure of the ease, with which magnetic lines of force pass through a given material. The ability of a material to concentrate magnetic flux is called permeability and its symbol is the Greek lower case letter μ. Any material that is easily magnetized tends to concentrate magnetic flux.
What are some permeability examples?
Some Permeability examples include materials such as paper, cardboard, cotton, wool and sponges; and natural elements such as feathers of birds, wheat, sand and earth. Permeability is a physical property that allows some materials to be traversed by a fluid, in a limited period of time, and without this implying a change in its molecular ...
What does permeability mean?
What Does Permeability Mean? Permeability is the property of a material to allow fluids (such as water, water vapor or oil) to diffuse through it to another medium without being chemically or physically affected. Permeability causes deterioration of material longevity and acceleration of the corrosion process.
What does permeability mean in Earth Science?
Permeability in fluid mechanics and the Earth sciences (commonly symbolized as k) is a measure of the ability of a porous material (often, a rock or an unconsolidated material) to allow fluids to pass through it.. The permeability of a medium is related to the porosity, but also to the shapes of the pores in the medium and their level of connectedness.. Fluid flows can be influenced in ...
What is the definition of permeability?
Permeability is the property of medium or material which measures the easiness offered to pass the magnetic flux when an external magnetic filed is applied. That is the definition of permeability. But, if you want to know in detail about permeability, then you need go through the below tutorial.
What is permeability example?
An example of permeability is how fast water flows through a porous rock. The property of a porous substance, as rock or a membrane, of allowing the flow of a fluid through it. The measure of the ease with which a magnetic field can establish magnetic induction in a particular material. The property of being permeable.
What is permeability Class 11?
Hint: The permeability of a membrane refers to the property of the membrane by which it allows the only selective substance to pass through it.
What is a permeability in Physics?
Permeability is a material's ability to enable magnetic flux to pass through it when it is put inside a magnetic field, where magnetic flux is the number of magnetic lines of force that may pass through a particular surface. Permeability is represented by the Greek letter m, and it is measured in Farads/Meters (F/ M).
What is permeability and its unit?
Magnetic permeability (μ) = B/H. Where B = magnetic intensity and H = magnetising field. The SI unit of magnetic permeability is henries per meter (H/m) or newtons per ampere squared (N⋅A−2).
What is SI unit of permittivity?
Units. The standard SI unit for permittivity is farad per meter (F/m or F·m−1).
What is permeability and permittivity?
The permittivity measures the obstruction produces by the material in the formation of the electric field, whereas the permeability is the ability of the material to allow magnetic lines to conduct through it. The permittivity is represented by ε whereas μ represents the permeability.
What is permeability and their types?
Permeability is a broad term that includes different types such as magnetic permeability, rocks permeability, and membrane permeability. However, all these types represent the passage of fluids (liquids or gases) through pores.
What is the formula for permeability?
The formula for Magnetic Permeability formula is given as: Magnetic Permeability (μ) = B/H It is measured in Henries per metre (h/m) or newtons per ampere square.
What is permeability and porosity?
Porosity: is a measure of the void spaces in a material. Permeability: a measure of the ability of a material (such as rocks) to transmit fluids. Porosity and permeability are related properties of any rock or loose sediment.
What is the value of permeability?
The permeability of free space, μ0, is a physical constant used often in electromagnetism. It is defined to have the exact value of 4π x 10-7 N/A2 (newtons per ampere squared).
What is the best explanation of permeability?
Permeability is the quality or state of being permeable—able to be penetrated or passed through, especially by a liquid or gas. The verb permeate means to penetrate, pass through, and often become widespread throughout something.
What is water permeability?
Permeability is therefore a measure of the ability of water to move through a rock.
What is permeability in biology?
Permeability refers to the ease with which molecules cross biological membranes. It may also refer to the ease with which ions or molecules pass through the pore of channel proteins.
What is the best explanation of permeability?
Permeability is the quality or state of being permeable—able to be penetrated or passed through, especially by a liquid or gas. The verb permeate means to penetrate, pass through, and often become widespread throughout something.
What is the soil permeability?
The permeability of soil describes how water (or other liquid) and air are able to move through the soil. In the case of rainfall or irrigation, water moves very easily through highly permeable soils and very slowly through soils with low permeability.
What is permeability of the cell membrane?
The permeability of a membrane can be defined as the passive diffusion rate of permeated molecules across the biomembrane. It is unanimously accepted that permeability of any specific molecule depends mainly on charge number, polarity, size, and to some extent, to the molar mass of the molecule.
What is relative permeability?
Relative permeability, denoted by the symbol#N#μ r {displaystyle mu _ {mathrm {r} }}#N#, is the ratio of the permeability of a specific medium to the permeability of free space μ0 :
What is the permeability of free space?
The permeability constant μ0, also known as the magnetic constant or the permeability of free space, is the proportionality between magnetic induction and magnetizing force when forming a magnetic field in a classical vacuum .
What is the measure of magnetization that a material obtains in response to an applied magnetic field?
In electromagnetism, permeability is the measure of magnetization that a material obtains in response to an applied magnetic field. Permeability is typically represented by the (italicized) Greek letter μ. The term was coined in September 1885 by Oliver Heaviside. The reciprocal of permeability is magnetic reluctivity.
What is the property of an object that causes it to create a magnetic field in opposition of an externally applied magnetic?
Diamagnetism is the property of an object which causes it to create a magnetic field in opposition of an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their nuclei, thus changing the magnetic dipole moment in the direction opposing the external field. Diamagnets are materials with a magnetic permeability less than μ0 (a relative permeability less than 1).
What is diamagnetism?
Consequently, diamagnetism is a form of magnetism that a substance exhibits only in the presence of an externally applied magnetic field.
What is the term for a form of magnetism that occurs only in the presence of an externally applied magnetic?
Paramagnetism . Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field. Paramagnetic materials are attracted to magnetic fields, hence have a relative magnetic permeability greater than one (or, equivalently, a positive magnetic susceptibility ).
What is the ratio of the imaginary to the real part of the complex permeability?
The ratio of the imaginary to the real part of the complex permeability is called the loss tangent ,
What is the unit of permeability?
The standard unit for permeability is the Darcy (d) or, more commonly, the millidarcy (md). Relative permeability is a dimensionless ratio that reflects the capability of oil, water, or gas to move through a formation compared with that ...
What is the basis for permeability determination?
The fundamental relationship given by Henry is the basis for permeability determination. Darcy's law originates from the interpretation of the results of the flow of water through an experimental apparatus, shown in Figure 1. In this experiment, water was allowed to flow downward through the sand pack contained in an iron cylinder. Manometers located at the input and output ends measured fluid pressures, which were then related to flow rates to obtain the following fundamental Darcy's law:
How does the Klinkenberg permeameter work?
The permeameter works on the principle of transient analysis of pressure pulse decay in which Klinkenberg permeability is determined as a function of gas (ideally helium) pressure decay. This equipment consists of a reference cell of known volume that charges the core sample with gas. A downstream valve vents the gas pressure, and pressure change as a function of time is recorded. A typical pressure drawdown plot (Jones, 1990) [citation needed] is shown in Figure 5. Advantages of the unsteady-state method include the ability to determine simultaneously (from Figure 5) the Klinkenberg permeability ( k∞ helium slippage factor (β He ), and the inertial coefficient (β). A comparison of the steady-state method to the unsteady-state method is presented in Table 1.
How do random errors affect permeability?
Systematic and/or random errors may affect the accuracy of permeability determined from any method, whether laboratory core or well test analysis. Uncertainty in the models used for permeability determination and input variables can result only in random errors if the same analytical technique, equipment calibration, and quality control scenario are considered. Amaefule and Keelan have shown that random errors can be addressed through stochastic modeling in which uncertainty can be assigned to the independent variables by multiple measurements and statistical calculations. Typically, accuracy of measured permeabilities decline at low and high values and are usually within ±5%.
How is permeability controlled in sandstone?
Permeability is controlled in sandstone by grain size, grain orientation, packing arrangement, cementation, clay content, bedding, and grain size distribution and sorting. In carbonates, permeability is a function of the degree of mineral alteration (such as dolomitization), porosity development, and fractures.
What is the most commonly used method to average horizontal permeability?
The most commonly used method to average horizontal permeability is the arithmetic average . Comparison of core permeabilities shows that arithmetic average permeabilities values generally agree with well test permeabilities.
What is the relationship between porosity and permeability?
Prominent among these relationships is the work of Kozeny, which considered the porous media as a bundle of capillary tubes of equal length. Modifications to account for tortuosity of flow paths in the porous media have been proposed, including the Carman-Kozeny model (1938). Unfortunately, only qualitative results have been obtained using these permeability-porosity relationships because of the complexity of the geometry of the porous media .
What is the measure of how interconnected the individual pore spaces are in a rock or sediment?
Permeability. The ease with which fluid is transmitted through a rock's pore space is called permeability. Although a rock may be very porous, it is not necessarily very permeable. Permeability is a measure of how interconnected the individual pore spaces are in a rock or sediment. A sandstone is typically porous and permeable.
Why are shale rocks porous?
Shales are porous but have a lower permeability because the finer grain size creates smaller pore spaces. Igneous rocks tend to have low porosity and low permeability unless they are highly fractured by tectonic processes. Previous Glaciers and Glaciation. Next The Water Table. The Earth's Exterior.
What is permeability in electromagnetism?
In electromagnetism, permeability is the measure of the resistance of a substance against the formation of a magnetic field. This constant is very important, since one of important magnetic properties is the relative permeability (dimensionless), the ratio of the permeability in ...
What is the property of magnetic susceptibility?
A closely related property of materials is magnetic susceptibility, which is a dimensionless proportionality factor that indicates the degree of magnetization of a material in response to an applied magnetic field. Neither μr nor χ are constants, , as they can vary with the position in the medium.
What is magnetic permeability?
In simpler words, we can define magnetic permeability as “the extent to which magnetic field lines can enter substance.” or “The power of conducting magnetic field lines by a substance.”. It is denoted by the Greek alphabet μ.
What is the permeability of free space?
The permeability of free space is called Permeability constant and has the value μ 0 = 4𝝅×10 -7 H/m It is a scalar quantity of isotropic medium and second rank tensor for anisotropic medium. Magnetic permeability plays an important role in classifying the magnetization property of a material. The material is said to be diamagnetic if its magnetic permeability is less than μ 0. Similarly, the material is said to be paramagnetic if its magnetic permeability is greater than μ 0.
What is the measure of the ability of a material to allow the formation of magnetic lines of force or magnetic field within?
In electrostatics, permeability is the measure of the ability of the material to allow the formation of magnetic lines of force or magnetic field within. It speaks on the ability of magnetization that a material possesses for the applied magnetic field.
What is the relative permeability of a vacuum?
The relative permeability of vacuum is 1.
What is the least possible value of permittivity?
The vacuum characterizes the least possible value of Permittivity. This is commonly referred to as the Permittivity of Free Space or electric constant. Denoted by ϵ 0 and has the value 8.85✕ 10 -12 Farad/meter. The opposition against the formation of electric field lines is evident in dielectrics too. The permittivity of a dielectric is represented by the ratio of its absolute permittivity to electric constant and is commonly called relative permittivity. It is a dimensionless quantity and is given as:
What is selective permeability?
Selective permeability is a property of cellular membranes that only allows certain molecules to enter or exit the cell. This is important for the cell to maintain its internal order irrespective of the changes to the environment. For example, water, ions, glucose and carbon dioxide may need to be imported or exported from ...
Why is selective permeability important?
Selective permeability is crucial for creating a distinctly different environment inside the cell as compared to the extracellular matrix. It is equally relevant in maintaining the integrity of various organelles inside the cell. Each organelle is a small compartment with a specialized function, requiring optimal concentrations of proteins, ...
What is the cell membrane made of?
Currently the cell membrane is said to be made of a selectively permeable phospholipid bilayer whose hydrophillic domains face the aqueous environments inside and outside the cell, and hydrophobic domains face each other to form a bilayer. This lipid bilayer is punctuated by cholesterol molecules, glycolipids, and proteins ...
Why is permeability important in eukaryotic cells?
Selectively permeability of membranes is particularly important for transport across the nuclear membrane in eukaryotic cells. Proteins, nucleic acids, and nucleotides involved in transcription must be selectively and efficiently transported into the nucleus and the products of transcription must be exported in a timely manner.
How does transmembrane transport work?
For example, in most cells, there is a large excess of sodium ions in the extracellular environment along with an excess of potassium ions inside the cell. This is achieved by a transmembrane enzyme called the Na+/K+ ATPase, that catalyzes the movement of three Na+ ions outside the cell along with the import of two K+ ions. For each such transport cycle, the enzyme uses the energy released from the conversion of one molecule of ATP into ADP. This is called primary active transport, where the movement is directly coupled to the hydrolysis of a high-energy phosphate bond. A similar process is used to pump protons against their concentration gradient and this is a crucial part of both photosynthesis and cellular respiration.
What is the nuclear membrane?
The Nuclear membrane has a structure different from all the other membranes of the cell. It has nuclear pore complexes – basket-like multiprotein complexes that are freely permeable to water but stringently mediate nuclear transport of macromolecules.
How are cell membranes visualized?
Cell membranes are not easily visualized using light microscopes. Therefore, hypotheses about their existence only arose in the late 19th century, nearly two hundred years after the first cells has been observed. At various points, different models have attempted to explain how the structure of the membrane supports its function. Initially, the membrane was supposed to be a simple lipid layer demarcating the cytosol from the extracellular region. Afterwards, models included semipermeable gel-like regions in a lipid sea to explain the movement of water but not charged particles. Thereafter, the presence of pores was proposed, allowing small molecules to move freely.
What is Magnetic Permeability?
Magnetic permeability is a property that basically allows magnetic lines of force to pass through a material.
What material has a constant relative permeability greater than 1?
Paramagnetic Materials. Paramagnetic materials have a constant relative permeability slightly greater than 1, that’s why when a paramagnetic material placed in an external field it gets feebly magnetized in the direction of the magnetic field. Example: Platinum. Read more about it here: Paramagnetic Materials .
What is the permeability of free space?
Permeability of free space also known as the permeability of air or vacuum is represented by μ 0 =B 0 /H
What are the factors that affect magnetic permeability?
Permeability also depends on several factors such as the nature of the material, humidity, position in the medium, temperature, and frequency of the applied force. Magnetic permeability is always positive and can vary with a magnetic field. Meanwhile, the opposite of magnetic permeability is magnetic ...
Overview
Relative permeability and magnetic susceptibility
Relative permeability, denoted by the symbol , is the ratio of the permeability of a specific medium to the permeability of free space μ0:
where 4π × 10 H/m is the magnetic permeability of free space. In terms of relative permeability, the magnetic susceptibility is
The number χm is a dimensionless quantity, sometimes called volumetric or bulk susceptibility, t…
Explanation
In the macroscopic formulation of electromagnetism, there appears two different kinds of magnetic field:
• the magnetizing field H which is generated around electric currents and displacement currents, and also emanates from the poles of magnets. The SI units of H are amperes/meter.
• the magnetic flux density B which acts back on the electrical domain, by curving the motion of charges and causing electromagnetic …
Diamagnetism
Diamagnetism is the property of an object which causes it to create a magnetic field in opposition of an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their atom's nuclei, thus changing the magnetic dipole moment in the direction opposing the external field. Diamagnets are materials with a magnetic permeability less than μ0 (a relative permeability less than 1).
Paramagnetism
Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field. Paramagnetic materials are attracted to magnetic fields, hence have a relative magnetic permeability greater than one (or, equivalently, a positive magnetic susceptibility).
The magnetic moment induced by the applied field is linear in the field strength, and it is rather weak. It typically requires a sensitive analytical balance to detect the effect. Unlike ferromagnets, …
Gyromagnetism
For gyromagnetic media (see Faraday rotation) the magnetic permeability response to an alternating electromagnetic field in the microwave frequency domain is treated as a non-diagonal tensor expressed by:
Values for some common materials
The following table should be used with caution as the permeability of ferromagnetic materials varies greatly with field strength. For example, 4% Si steel has an initial relative permeability (at or near 0 T) of 2,000 and a maximum of 35,000 and, indeed, the relative permeability of any material at a sufficiently high field strength trends toward 1 (at magnetic saturation).
See also
• Antiferromagnetism
• Diamagnetism
• Electromagnet
• Ferromagnetism
• Magnetic reluctance
Theoretical Background
- The fundamental relationship given by Henry is the basis for permeability determination. Darcy's law originates from the interpretation of the results of the flow of water through an experimental apparatus, shown in Figure 1. In this experiment, water was allowed to flow downward through the sand pack contained in an iron cylinder. Manometers located at the input and output ends meas…
Factors Controlling Permeability
- Pore geometry
Permeability is a function of the geometry of the pore structure of the porous media. Permeability is controlled in sandstone by grain size, grain orientation, packing arrangement, cementation, clay content, bedding, and grain size distribution and sorting. In carbonates, permeability is a functio… - Bedding
Directional and local variations of permeability generally exist in reservoirs. Permeability perpendicular to bedding planes (vertical permeability) is typically lower than horizontal permeability (parallel to the bedding planes).
Permeability Determination
- Theoretical basis
Permeability is not measured; it is calculated. Therefore, although it is a rock property and a constant for a given core sample, permeability values can vary according to the model and boundary conditions used in the calculation. To determine permeability, Darcy's law inherently a… - Gas slippage and inertial effect
When gas is used to determine permeability at low mean pressure, the resistance to flow from drag is very low, resulting in “gas slip conditions.” Consequently, permeability calculated from Darcy's law will be too high and must be corrected using the Klinkenbergmodel. When gas perm…
See Also
External Links