Two thermocouples, one of them a known standard, are placed in an air stream whose temperature is

Question:

Two thermocouples, one of them a known standard, are placed in an air stream whose temperature is varying sinusoidally. The temperature responses of the two thermocouples are recorded at a number of frequencies, with the phase angle between the two measured as shown below. The standard is known to follow first-order dynamics arid to have a time constant of 0.15 mm when operating in the air stream. From the data, show that the unknown thermocouple also is first order and find its timeconstant.