A fine wire 0.025 mm in diameter and 15 cm long is to be used to sense flow velocity by measuring the electrical heat that can be dissipated from the wire when placed in an airflow stream. The resistivity of the wire is 70 μ Ω ∙ cm. The temperature of the wire is determined by measuring its electric resistance relative to some reference temperature To so that
R = Ro [l + a(T −To)]
For this particular wire the value of the temperature coefficient a is 0.006oC−1. The resistance can be determined from measurements of the current and voltage impressed on the wire, and
R= E / I
Suppose a measurement is made for air at 20oC with a flow velocity of 10 m/s and the wire temperature is 40oC. What values of voltage and current would be measured for these conditions if Ro is evaluated at To = 20oC? What values of voltage and current would be measured for the same wire temperature but flow velocities of 15 m/s and 20 m/s?