MEASURING INSTRUMENT Q.8

If the cold junction of thermocouple is lowered, then the neutral temperature [1] Increase

Q.9

[JIPMER 2002]

[2] Approaches inversion temp. [3] Decreases

[4] Remains the same

A thermoelectric refrigerator works on [1] Joule effect

[2] Seebeck effect

[JIPMER 2002] [3] Peltier effect

[4] Thermionic emission

Q.10 The neutral temperature of a thermocouple is 350ºC when the cold junction is at 0ºC. When the cold junction is immersed in a bath of 30ºC, the inversion temperature is [KERALA (MED) 2002] [1] 700ºC

[2] 600ºC

[3] 350ºC

[4] 670ºC

Q.11 Two ends of a conductor are at different temperature the electromotive force generated between two ends is [MP PMT 2001; MP PET 2002] [1] Seeback electro motive force (emf)

[2] Peltier electro motive force (emf)

[3] Thomson electro motive force (emf)

[4] None of these

1 2 βt , If temperature of cold junction is 0ºC then temperature of inversion is (if a = 500.0 mV/ºC, 2 b = 5.0mV/Square ºC) [DCE 2001]

Q.12 e = at –

[1] 100ºC

[2] 200ºC

[3] 300ºC

[4] 400ºC

Q.13 For a thermocouple the neutral temperature is 270º when its cold junction is at 20ºC. What will be the neutral temperature and the temperature of inversion when the temperature of cold junction is increased to 40ºC [KERALA PET - 2001] [1] 290ºC, 580ºC

[2] 270ºC, 580ºC

[3] 270ºC, 500ºC

[4] 290ºC, 540ºC

Q.14 In the Seeback series Bi occurs first followed by Cu and Fe among other. The Sb is the last in the series. If E1 be the thermo emf at the given temperature difference for Bi-Sb thermocouple and E2 be that for Cu–Fe thermocouple, which of the following is true [J & KCEET 2000] [1] E1 = E2

[2] E1 < E2

[3] E1 > E2

[4] Data is not sufficient to predict it

Q.15 In a given thermocouple the temperature of the cold junction is 20ºC while the neutral temperature is 270ºC. What will be the temperature of inversion [AMU (Engg) 2000] [1] 540ºC

[2] 520ºC

[3] 500ºC

[4] 420ºC

Q.16 Consider the following two statements A and B, and identity the correct choice of given answer. A. Thermo e.m.f is minimum at neutral temperature of a thermocouple

[EAMCE (MED.) 2000]

B. When two junctions made of two different metallic wires are maintained at different temperature, an electric current is generated in the circuit. [1] A is false and B is true [2] A is true and B is false

[3] Both A and B are false [4] Both A and B are true

Q.17 Two different metals are end to end. One end is kept at constant temperature and the other end is heated to a very high temperature. The graph depicting the thermo e.m.f is [DCE 2000]

[1]

[2]

[3]

[4]

Q.18 If 96500 coulombs of electricity liberates one gram equivalent of any substance, the time taken for a current of 0.15 amperes to deposit 20mg of copper from a solution of copper sulphate is (Chemical equivalent of copper = 32) [1] 5 min 20 sec

[2] 6 min 42 sec

[3] 4 min 40 sec

[KERALA (ENGG.) 2002] [4] 5 min 50 sec