Which of the following gauges can measure the pressure in the range of \(10^{-10}\) to \(10^{-3}\) Torr ?
MH SET - 2019, SET Exam - 2019,
Answer: D
The gauge is the Ionization gauge.
A hot-cathode ionization gauge of the Bayard-Alpert type measures the ion current produced by electrons colliding with gas molecules, which is proportional to the pressure from about \(10^{-3}\) down to \(10^{-10}\) Torr.
The Pirani gauge works only down to about \(10^{-3}\) Torr and the McLeod gauge down to about \(10^{-5}\) Torr, and the cold-cathode Penning gauge typically covers about \(10^{-2}\) to \(10^{-7}\) Torr, not the full range down to \(10^{-10}\).
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