## Answer 4.3

#### The average power of thermal noise for given by:
Nav = kTB
and hence is directly proportional to temperature.
Thus for a change in temperature from room temperature (273 + 17) = 290oK to (273 – 40) = 233oK we would expect the thermal noise power to decrease by a factor 233 / 290 = 0.803 or 0.95 dB as the electron motion slows down.
At a temperature of (273 + 80) = 353oK the noise power will increase by a factor 353/290 = 1.217 or 0.85 dB.