# Symbols:Greek/Mu

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## Mu

The $12$th letter of the Greek alphabet.

Minuscule: $\mu$
Majuscule: $\Mu$

The $\LaTeX$ code for $\mu$ is \mu .

The $\LaTeX$ code for $\Mu$ is \Mu .

### micro-

$\mu$

The Système Internationale d'Unités symbol for the metric scaling prefix micro, denoting $10^{\, -6}$, is $\mu$.

### Micron

$\mu$

Before $1967$, the micrometre $\mu \mathrm m$ was called the micron.

Its symbol was $\mu$.

Its $\LaTeX$ code is \mu .

### Expectation

$\mu$

Often used to denote the expectation of a given random variable.

### Linear Density

$\mu$

Used to denote the linear density of a given one-dimensional body:

$\mu = \dfrac m l$

where:

$m$ is the body's mass
$l$ is the body's length.

### Poisson Distribution

$\mu$

Used as an alternative to $\lambda$ to denote the parameter of a given Poisson distribution.

### Moment of Discrete Random Variable

$\mu'_n$

Let $X$ be a discrete random variable.

Then the $n$th moment of $X$ is denoted $\mu'_n$ and defined as:

$\mu'_n = \expect {X^n}$

where $\expect {\, \cdot \,}$ denotes the expectation function.

The $\LaTeX$ code for $\mu'_n$ is \mu'_n .

### Micrometre

$\mu \mathrm m$

The symbol for the micrometre is $\mu \mathrm m$.

$\mu$ for micro
$\mathrm m$ for metre.

Its $\LaTeX$ code is \mu \mathrm m .

### Vacuum Permeability

$\mu_0$

The vacuum permeability is the physical constant denoted $\mu_0$ defined as:

$\mu_0:= \dfrac {2 \alpha h} {e^2 c}$

where:

$e$ is the elementary charge
$\alpha$ is the fine-structure constant
$h$ is Planck's constant
$c$ is the speed of light defined in $\mathrm m \, \mathrm s^{-1}$

Of the above, only the fine-structure constant $\alpha$ is a measured value; the others are defined.

It can be defined as the capability of a magnetic field to permeate a vacuum.

From Value of Vacuum Permeability, it has the value:

$\mu_0 = 1 \cdotp 25663 \, 70621 \, 2 (19) \times 10^{-6} \, \mathrm H \, \mathrm m^{-1}$ (henries per metre)

The $\LaTeX$ code for $\mu_0$ is \mu_0 .

## Sources

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