Question

The primary standard instrument used for calibrating vacuum is:

• A. McLeod gauge
• B. Dead weight tester
• C. Thermocouple gauge
• D. Knudsen gauge

Hint:

McLeod gauge = primary vacuum standard, based on gas compression and Boyle’s law.

Answer 1

The Correct Option is A

The primary standard instrument used for calibrating vacuum is the McLeod gauge. This instrument is used to measure low pressures by compressing a known volume of gas, allowing the pressure to be measured accurately. The McLeod gauge is known for its precision and is widely used in laboratory settings for calibration purposes because it can provide accurate readings without being affected by different types of gases, unlike some other gauges which rely on gas properties. Other options such as the Dead weight tester, Thermocouple gauge, and Knudsen gauge are used for different purposes and do not serve as the primary standard for vacuum calibration.