Pressure of the order of 10''' torr can be measured by
A. Bourdon tube
B. Pirani Gauge
C. micro-manometer
D. ionisastion gauge
Answer: Option D
Solution (By Examveda Team)
Pressures of the order of 10⁻⁷ torr (very high vacuum) are extremely low and cannot be measured by ordinary pressure-measuring devices.A Bourdon tube is used for measuring relatively high pressures and is unsuitable for vacuum measurements.
A micro-manometer is used for small pressure differences but not for very high vacuum ranges.
A Pirani gauge can measure low pressures only up to about 10⁻³ torr.
An ionisation gauge operates on the principle of ionizing gas molecules and is specifically designed to measure very low pressures (high vacuum) of the order of 10⁻⁷ torr and below.
Hence, the correct answer is ionisation gauge.

Pirani gauges (thermal conductivity) or convectron gauges measures pressure of order of 10 raise to power -4 to 10 torr
McLeod gauges are used to very low pressure (down to 10 raise to power -6 torr)
Ionization gauges suitable for ultra high vacuum( below 10 raise to power -3)
From vacuum to hig(0.6 bar/8.7psi to 7000bar/100000psi) (bouden gauges)
1torr=133.32pa=0.01933psi=0.00133bar =.00132atm
Capsule pressure gauges( very low gas pressure (UpTo 0.6bar/8.7psi)
Diaphragm pressure gauge (low to medium pressure (-1 to 40bar)
1bar=14.504psi=100000pascals=750.062torr
Bellows gauges 0.1mbar to 16 bar
Plz discuss all the pressure measurement gauge