Question

(A) Thermo emf depends on the nature of metals and temperature of junctions.
(B) By a thermoelectric thermometer we can measure the temperature of the sun.

A. Both A and B are true
B. Both A and B are false
C. A is true but B is false
D. A is false B is true

Answer 1

Hint: Check first whether the first statement is true or not and then go for the second one, after checking and comparing, write your final answer.

Complete Step-by-Step solution:
Statement A is true:
Thermo emf depends on the nature of metals and temperature of junctions. When the temperature difference between the two junctions of a thermocouple changes then the emf produced between them is known as thermo emf and this thermo emf also changes with the change in temperature difference, also for dissimilar metals the thermo emf produced is also different.

Statement B is false:
By a thermoelectric thermometer we cannot measure the temperature of the sun. A radiation thermometer or a pyrometer can be used to measure very high temperatures such as the temperature of the sun. A thermoelectric thermometer is based on the principle of seebeck effect.
Hence, the statement A is true but B is false.

So, the correct option is C.

Note – Whenever checking for any statement to be true or false, first know about the given device completely, as mentioned in the solution that a thermo emf is developed when the temperature difference between the two junctions of a thermocouple changes. Also, the thermoelectric thermometer cannot be used to measure temperature of the sun, it is used to measure rapidly changing temperature of very small objects.