Mean Free Path and RMS Speed

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Mean Free Path and RMS Speed: Overview

This topic contains concepts like Time for Successive Collisions between Walls, and Mean Free Path.

Important Questions on Mean Free Path and RMS Speed

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The mean free path of molecules of a certain gas at STP is 1500d, where d is the diameter of the gas molecules. While maintaining the standard pressure, the mean free path of the molecules at 373 K is approximately:

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In a gas at STP, if n is the number density of the molecules and r is the radius of the molecule, then the mean free path of the molecule is inversely proportional to

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The collision frequency of nitrogen molecule in a cylinder containing at 2.0 atm pressure and temperature 17°C is approximately: (Take radius of a nitrogen molecule is 1.0 )

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Time for successive collisions between walls :-

(ii) Time for two successive collision between the walls is.

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Time for successive collisions between walls ;-

(i) When there is collision between two walls then charge in momentum per second is along X- axis.

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Derive the formula for time for successive collision between the walls of the container with the molecule.

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For a gas with n number of molecules per unit volume, Suppose the molecules of a gas are spheres of diameter d  the average speed of each molecule is v. The time between two successive collisions is on the average Γ=1nπvd2

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The mean free path (λ) of a gas sample is given by:

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If the temperature and pressure of a gas is doubled the mean free path of the gas molecules

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For a molecule of an ideal gas, the number density is 22×108 cm-3 and the mean free path is 10-2π cm. The diameter of the gas molecule is

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Consider an ideal gas confined in an isolated closed chamber. As the gas undergoes an adiabatic expansion, the average time of collision between molecules increases as Vq, where V is the volume of the gas. The value of q is :- γ=CpCv

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Define the following 

Mean free path

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Define the following

Free path

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A container is divided into two equal part I and II by a partition with small hole of diameter d. The two partitions are filled with same ideal gas, but held at temperature TI=150K and TII=300K by connecting to heat reservoirs. Let λI and λII be the mean free paths of the gas particles in the two parts such that d>>λI and d>>λII. Then λIλII is close to.

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At any instant, the position and velocity vectors of two particles are r1,r2andv1,v2 respectively. They will collide if :

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In the following a statement of Assertion is followed by a statement of Reason.

Assertion: Mean free path of a gas molecule is inversely proportional to the density of gas.

Reason: Path of a gas molecule between two adjacent collision is straight line.

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Consider an ideal gas confined in an isolated closed chamber. As the gas undergoes an adiabatic expansion, the average time of collision between molecules increases as Vq , where V is the volume of the gas. The value of q is γ=CPCv

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Which of the following is/are correct regarding mean free path ?

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Which of the following is/are correct regarding mean free path ?

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Air becomes conducting when the pressure ranges between