The advantages of the thermoelectric thermometer include the following characteristics except that it

Analyze the question: We need the option that is NOT an advantage of a thermoelectric thermometer (thermocouple).

Concept: A thermocouple is made from two different metals joined at two junctions. A temperature difference between the junctions produces an e.m.f. that is used to measure temperature.

Advantages of a thermocouple thermometer:

• It has a very small junction, so it has a low heat capacity. It responds quickly and can follow rapidly changing temperatures (A).
• It has a very wide range, from very low to very high temperatures (for example, about -200°C to over 1500°C) (B).
• The small junction can measure temperature almost at a point (C).
• It is robust and can be connected to remote or digital readouts.

Disadvantages:

• It is not very sensitive. The e.m.f. produced is only a few microvolts to millivolts per degree, so it needs a sensitive voltmeter or potentiometer.
• It is not as accurate as a platinum resistance thermometer, and it needs a reference junction.

Checking the options:

• A: advantage (fast response)
• B: advantage (wide range)
• C: advantage (point measurement)
• D: "is fairly sensitive". Thermocouples produce very small e.m.f.s, so this is not generally listed as an advantage. This is the exception.

Tip: Remember the thermocouple's strengths as "fast, wide range, point-sized". Sensitivity is not one of them. When you see "except" questions, look for the one property that does not fit the usual list.