Key Difference – Magnetic Permeability vs Susceptibility
Magnetic permeability and susceptibility are quantitative measures of magnetic properties of materials. The key difference between magnetic permeability and susceptibility is that magnetic permeability describes the ability of a material to support the formation of a magnetic field inside itself whereas susceptibility describes whether a material is attracted to a magnetic field or is repelled from it. Magnetic susceptibility is a dimensionless measure.
CONTENTS
1. Overview and Key Difference
2. What is Magnetic Permeability
3. What is Magnetic Susceptibility
4. Side by Side Comparison – Magnetic Permeability vs Susceptibility in Tabular Form
5. Summary
What is Magnetic Permeability?
Magnetic permeability of a material is the ability of a material to support the formation of a magnetic field inside itself. Therefore, it is also known as the degree of magnetization (the response towards an external magnetic field). The magnetic permeability is denoted by “μ”. The SI unit for the representation of magnetic permeability is Henries per meter (H/m or H·m−1). This unit is equivalent to Newtons per ampere squared (N·A−2).
The magnetic permeability is a relative measurement that is taken with respect to the magnetic permeability of a vacuum. The magnetic permeability of a vacuum is named as the magnetic permeability constant and is denoted by “μ0”. It is a measure of the resistance observed in a vacuum when generating a magnetic field inside that vacuum. The value of this constant is 4π × 10−7 H·m−1.
Figure 1: Magnetic Permeability in Different Materials
Different materials have different values for their magnetic permeability. For example, a diamagnetic material has a relative magnetic permeability less than 1 whereas a paramagnetic material has a value slightly higher than 1. This means when a paramagnetic material is placed under the influence of an external magnetic field, it becomes slightly magnetized (to a direction as same as in the external magnetic field). But ferromagnetic materials have no relative permeability.
What is Magnetic Susceptibility?
Magnetic susceptibility is the measure of magnetic properties of a material which indicates whether the material is attracted or repelled from an external magnetic field. This is a quantitative measurement of the magnetic properties.
Different materials have different values for the magnetic susceptibility. Paramagnetic materials have a magnetic susceptibility greater than zero whereas diamagnetic materials have a value less than zero. This means diamagnetic materials tend to get repelled from a magnetic field while a paramagnetic material is attracted to a magnetic field. The magnetic susceptibility of a material is given by the following relationship.
M = Xm.H
M is the magnetic moment per unit volume of the material and H is the intensity of the external magnetic field. Xm indicates magnetic susceptibility.
What is the Difference Between Magnetic Permeability and Susceptibility?
Magnetic Permeability vs Susceptibility |
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| Magnetic permeability of a material is the ability of a material to support the formation of a magnetic field inside itself. | Magnetic susceptibility is the measure of magnetic properties of a material which indicates whether the material is attracted or repelled from an external magnetic field. |
| Units of Measurement | |
| Magnetic permeability is measured by the SI unit Henries per meter (H/m or H·m−1) which is equivalent to Newtons per ampere squared (N·A−2). | The magnetic susceptibility is a dimensionless property. |
| Value for Diamagnetic Materials | |
| The value of magnetic permeability for diamagnetic materials is less than 1. | The value of magnetic susceptibility for diamagnetic materials is less than zero. |
| Value for Paramagnetic Materials | |
| The value of magnetic permeability for paramagnetic materials is greater than 1. | The value of magnetic susceptibility for paramagnetic materials is greater than zero. |
Summary – Magnetic Permeability vs Susceptibility
Magnetic permeability is given by the units Henries per meter, and magnetic susceptibility is a dimensionless property of materials. The key difference between magnetic permeability and susceptibility is that magnetic permeability describes the ability of a material to support the formation of a magnetic field inside itself whereas susceptibility describes whether a material is attracted to a magnetic field or is repelled from it.
Reference:
1. “Magnetic Permeability.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 25 Oct. 2016, Available here.
2. “Permeability (Electromagnetism).” Wikipedia, Wikimedia Foundation, 3 Apr. 2018, Available here.
3. “Magnetic Susceptibility.” Wikipedia, Wikimedia Foundation, 3 Apr. 2018, Available here.
Image Courtesy:
1.”Magnetic Permeability-no-caption” By MarLed (CC BY 1.0) via Commons Wikimedia