Question

Thermoelectric thermometers are advantageous than ordinary thermometer because:
A. They are less sensitive
B. The junctions are very small hence small portions of bodies can also be measured.
C. Thermal capacity of the junctions is small hence rapidly changing temperature can be measured.
D. b and c both are correct.

Answer 1

Hint: For this question we must know what are electronic thermometers and ordinary thermometers. Also, we should know what is their need so accordingly we can decide the advantages of one over the other. The electric thermometer works on the principle of electric resistance. It uses the concept that resistance of a metal changes with temperature. While the ordinary thermometer uses Liquid mercury which expands on heating and rises in the capillary.

Complete step by step answer:
Ordinary thermometers use liquid mercury for measuring temperatures. At first, the mercury is heated by the temperature of the body whose temperature is to be measured. This makes the mercury rise in the capillary of the thermometer. These thermometers work on the principle of thermal expansion, that when an object is heated it expands. This whole process takes a lot of time. Also the range of these temperatures is low between 35\[{}^\circ C\] to 45\[{}^\circ C\]. The electric thermometers use the principle of thermocouple for measuring temperatures. It consists of two wires of different material joined at each end to make separate junctions. One junction is placed where the temperature is to be measured and the other is at low constant temperature. These junctions are made into a micro size so as to measure the temperature of small things such as insects. The Thermal capacity of this junction is very small, this helps to measure the rapidly changing temperatures with high accuracy upto 0.025 degrees. The range of this temperature is very large as compared to ordinary temperatures. The range is found to be -200 \[{}^\circ C\]to 1600 \[{}^\circ C\]. From this we can conclude that electronic thermometers have many advantages over regular thermometers. Both option B and C are correct.
Therefore, the correct answer is option D.
Additional Information:
Among all the types of thermometers digital thermometers are highly accurate and fast.

Note:
If option D is not provided, students should make sure that it is a single or multiple choice question. If it is multiple choice both options should be selected carefully. The digital or electronic thermometers use Thermistors or Thermocouple as the sensor. It makes these thermometers accurate even while measuring small temperatures.