Answer 4.2
The average power of thermal noise for this case is given by:
N
av
=
kTB
= 1.38 x 10
23
x (273 + 17) x 20000 = 8.0 x 10
17
W or 131 dBm (dB relative to 1 mW)
Note that
o
C must be converted to
o
K