The following data pertains to the junction of a thermocouple wire used to measure the temperature of the gas stream.Density = 8500 kg/m3, specific heat = 325 J/kg K, thermal conductivity = 40 W/m K and the heat transfer coefficient between the junction and gas = 215 W/m2 K.

• A. nIf thermocouple junction can be approximated as 1 mm diameter sphere, determine how long it will take for the thermocouple to read 99% of the initial temperature difference
• B. 9.86 seconds
• C. 8.86 seconds
• D. 7.86 seconds
• E. 6.86 seconds