Questions and answers for exam Preparation

MCQs

Total Questions : 107 | Page 5 of 11 pages

Question 41. . Which of the following glass is used for 500-600?C temperature measurement by mercury-in-glass thermometer :

Lead glass
Normal grade
Borosilicate
Supennax

Discuss Question

Answer: Option D. -> Supennax

Question 42. . For measuring temperature in the range of ?20 to 600?C, following liquid is used in glass thermometer :

Mercury
Alcohol
Toluene
Pentane

Discuss Question

Answer: Option A. -> Mercury

Question 43. . Pick up false statement about liquid-inmetal thermometers :

Remote indication of temperature can't be given
Error is produced if capillary passes through hot zone
Error also occurs if instrument base is at high ambient temperature error can also creep in by the head of the liquid if the bulb is installed either above or below the Bourdon
(e) these are used for Industrial applications where accuracy is not so important.

Discuss Question

Answer: Option A. -> Remote indication of temperature can't be given

Question 44. . Twisting the thermocouple wires together and heat welding them :

Is the standard practice of making junction
Would result in noise generation
Cause small errors du-2; to local e.m.f. which may arise if the junction is too long
Would slow down the response

Discuss Question

Answer: Option C. -> Cause small errors du-2; to local e.m.f. which may arise if the junction is too long

Question 45. . Which of the following thermocouple generates highest e.m.f. for a given temperature :

Copper-constantan
Iron-constantan
Chromel-alumel
Platinum-rhodium platinum

Discuss Question

Answer: Option B. -> Iron-constantan

Question 46. . Protective coating by a suitable cover are applied over strain gauge in order to protect it against

Temperature rise
Dust and dirt
Moisture
Ageing

Discuss Question

Answer: Option C. -> Moisture

Question 47. . The resistance of strain gauge grid used in pressure transducers is of the order of

0.1 to 1 ohm
1 to 10 ohm
10 to 100 ohm
100 to 2000 ohm

Discuss Question

Answer: Option D. -> 100 to 2000 ohm

Question 48. . Pick up false statement :

Copper-constantan thermocouple is a stable couple resistant to both oxidising and reducing atmosphere, but needs protection from acidic vapours
Copper-constantan thermocouple is used as a reference standard for calibration purposes.
Iron-constantant couple can be made stable by using enamelled iron
Both wires of chromel-alumel thermocouples are prone to damage by sulphurous gases

Discuss Question

Answer: Option B. -> Copper-constantan thermocouple is used as a reference standard for calibration purposes.

Question 49. . During temperature changing conditions, quite appreciable difference, occurs between the -true-temperature and the measured temperature because of the time required for the transfer of heat through thermometer pockets (thermowells) to thermometer sensing element. This time lag is of the order of :