Process Control and Instrumentation

301. Which of the following thermocouples has the least temperature measurement range?

1. Copper-constantan
2. Chromel-alumel
3. Platinum-platinum/rhodium
4. Iron-constantan

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302. Which of the following thermocouples has the widest temperature measurement range?

1. Iron-constantan
2. Chromel-alumel
3. Copper-constantan
4. Platinum-platinum/rhodium

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303. Which of the following thermocouples is capable of measuring a temperature of -50°C?

1. Platinum-platinum + rhodium
2. Chromel-Alumel
3. Iron-constantan
4. Copper-constantan

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304. Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere?

1. Platinum-platinum + rhodium
2. Iron-constantan
3. Copper-constantan
4. Chromel-alumel

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305. Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature?

1. Platinum-platinum + rhodium
2. Iron-constantan
3. Chromel-constantan
4. All will give the same output

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306. Which of the following thermometers is not suitable for distant reading upto 60 metres?

1. Vapor pressure thermometer
2. Mercury in glass thermometer
3. Constant volume gas thermometer
4. Resistance thermometer

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307. Which of the systems having following transfer functions is stable?

1. 1/(S² + 2)
2. 1/(S² - 2s + 3)
3. 1/(S² + 2s + 2)
4. exp (-20s)/(S² + 2s - 1)

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308. Zirconia probe is used for the measurement of

1. Humidity of air
2. % CO₂ in flue gas
3. % O₂ in flue gas
4. Speed of a submarine

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309. Which thermocouple can be used to measure a temperature of around 1400°C?

1. Copper-constantan
2. Aluminium-Chromel
3. Platinum-platinum + rhodium
4. None of these

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310. With increase in temperature, the electrical conductivity of the platinum used in the resistance thermometer

1. Increases
2. Decreases
3. Remain constant
4. Increases exponentially

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