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Physical constants


Const = physconst(Name)


Const = physconst(Name) returns the constant specified in the Name argument. Valid values are 'LightSpeed', 'Boltzmann', or 'EarthRadius'. Values are in SI units.

Input Arguments


Character vector that indicates which physical constant the function returns. Values are not case sensitive.

Output Arguments


Value of physical constant specified in the input argument Name.


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Determine the wavelength of a 1 Ghz electromagnetic wave.

freq = 1e9;
lambda = physconst('LightSpeed')/freq
lambda =


Approximate the thermal noise power per unit bandwidth in the I and Q channels of a receiver.

Specify the receiver temperature and Boltzmann constant.

T = 290;
k = physconst('Boltzmann');

Compute the noise power per unit bandwidth, split evenly between the in-phase and quadrature channels.

Noise_power = 10*log10(k*T/2);

More About

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Physical Constants

This table lists the supported constants and their values in SI units.

'LightSpeed'Speed of light in vacuum299,792,458 m/s. Most commonly denoted by c.
'Boltzmann'Boltzmann constant relating energy to temperature1.38×1023 J/K. Most commonly denoted by k.
'EarthRadius'Mean radius of the Earth6,371,000 m

Extended Capabilities

Introduced in R2011a

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