A white noise w (t) of power spectral density N0/2

A white noise w (t) of power spectral density N0/2 is applied to a Butterworth low-pass filter of order n, whose magnitude response is defined by
(a) Determine the noise equivalent bandwidth for this low-pass filter, for the definition of noise equivalent bandwidth.)
(b) What is the limiting value of the noise equivalent bandwidth as n approachesinfinity?