Definition:First Radiation Constant

Definition

The first radiation constant is defined as:

$c_1 = 2 h c^2$

where:

$h$ denotes Planck's constant

$c$ denotes the speed of light.

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Symbol

$c_1$

The symbol for the first radiation constant is $c_1$.

The $\LaTeX$ code for \(c_1\) is c_1 .

Dimension

The first radiation constant has the dimension $\mathsf {M L^4 T^{-3} }$.

Units

The SI unit for the first radiation constant is given as watt (metres) squared per second: $\mathrm {W \, m^2}$

The CGS unit for the first radiation constant is given as ergs centimetre squared per second: $\mathrm {erg \, cm^2 \, s^{-1} }$

Value

The value of the first radiation constant is:

\(\ds c_1\)

\(=\)

\(\ds 2 h c^2\)

\(\ds \)

\(=\)

\(\ds 1 \cdotp 19104 \, 2972 \ldots \times 10^{-18} \, \mathrm {W \, m^2}\)

\(\ds \)

\(=\)

\(\ds 1 \cdotp 19104 \, 2972 \ldots \times 10^{-15} \, \mathrm {erg \, cm^2 \, s^{-1} }\)

Also defined as

The first radiation constant is also seen defined as:

$c_1 = 8 \pi h c$

where:

$h$ denotes the Planck's constant

$c$ denotes the speed of light.

This can be obtained from the conventional definition of first radiation constant by multiplying it by $\dfrac {4 \pi} c$.

Also see

• Definition:Second Radiation Constant

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