Discuss briefly the different physical principles used in temperature$-$measuring

instruments and give examples of instruments that use each of these principles.

$14\mathrm{.}2.($a$)$How are thermocouples manufactured? $($b$)$What are the main differences between

base metal and noble metal thermocouples? $($c$)$Give six examples of the materials

used to make base metal and noble metal thermocouples. $($d$)$Specify the international

code letter used to designate thermocouples made from each pair of materials that you

give in your answer to part $($c$).$

$14\mathrm{.}3.$Explain what each of the following are in relation to thermocouples: $($a$)$extension

leads, $($b$)$compensating leads, $($c$)$law of internediate metals, and $($d$)$law of

intermediate temperature.

$14\mathrm{.}4.$What type of base metal thermocouple would you recommend for each of the

following applications?

$($a$)$measurement of subzero temperatures

$($b$)$measurement in oxidizing atmospheres

$($c$)$measurement in reducing atmospheres

$($d$)$where high sensitivity measurement is required

$14\mathrm{.}5.$Why do thermocouples need protection from some operating environments and how is

this protection given? Discuss any differences between base metal and noble metal

thermocouples in the need for protection.