Perfect vacuum refers to a region that is completely devoid of particles. Pressure in perfect vacuum would be zero. On Earth, achieving a perfect vacuum is quite difficult in practice. In a modern physics laboratory with state-of-the-art vacuum systems, one may achieve a pressure of 1 nPa (1 × 10-º Pa). This is referred to as ultra-high vacuum. Suppose you have a vessel of volume 1 m³ filled with air at a temperature of 300 K (approximately room temperature). Suppose a vacuum system is used to pump air out of the vessel, reducing the pressure from an initial value of 101325 Pa (1 atm) to a final value of 1 nPA. Assume that the volume and temperature remain constant. Calculate the initial and final numbers of molecules in the vessel at atmospheric pressure and at ultra- high vacuum (1 nPa). Comment: Perhaps surprisingly, even at ultra-high vacuum there is still a large number of particles in the vessel: 0 « N¡ « N¡.

Perfect vacuum refers to a region that is completely devoid of particles. Pressure in perfect vacuum would be zero. On Earth, achieving a perfect vacuum is quite difficult in practice. In a modern physics laboratory with state-of-the-art vacuum systems, one may achieve a pressure of 1 nPa (1 × 10-º Pa). This is referred to as ultra-high vacuum. Suppose you have a vessel of volume 1 m³ filled with air at a temperature of 300 K (approximately room temperature). Suppose a vacuum system is used to pump air out of the vessel, reducing the pressure from an initial value of 101325 Pa (1 atm) to a final value of 1 nPA. Assume that the volume and temperature remain constant. Calculate the initial and final numbers of molecules in the vessel at atmospheric pressure and at ultra- high vacuum (1 nPa). Comment: Perhaps surprisingly, even at ultra-high vacuum there is still a large number of particles in the vessel: 0 « N¡ « N¡.

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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