= Harry Nyquist
{c}
= H. Nyquist
{c}
{synonym}
<Harry Nyquist> was an <electrical engineer> whose work connected communication engineering with physical and mathematical limits. His 1928 theory explained thermal electrical fluctuations using <thermodynamics> and <statistical mechanics>, agreeing with <John Bertrand Johnson>'s measurements.<Thermal Agitation of Electric Charge in Conductors by Harry Nyquist>[Abstract and concluding calculation]{ref}
In the classical regime $hf\ll k_B T$, an approximately constant <electrical resistance> $R$ at <temperature> $T$ produces an open-circuit <electric potential difference>[voltage] <expected value> square $\langle V^2\rangle=4k_BTR\,\Delta f$ over a one-sided <frequency> band of width $\Delta f$. Here $k_B$ is the <Boltzmann constant>. The formula connects <Johnson-Nyquist noise> with both the physical conductor and the <signal bandwidth> through which it is observed.<Thermal Agitation of Electric Charge in Conductors by Harry Nyquist>[Page 113, equations 4–8]{ref}
Back to article page
