question_answer

Suggest suitable methods for measuring the temperature (i) surface of the sun,    (ii) surface of the earth, (iii) an insect, and           (iv) liquid helium.

Answer:

                (i) By using total radiation pyrometer. (ii) By using a thermoelectric thermometer by embedding its hot junction in the earth. (iii) By using a thermoelectric thermometer by touching its hot junction with the insect. (iv) By using a magnetic thermometer which is based on Curie's law: the susceptibility of a paramagnetic material varies inversely with its absolute temperature.