The mean free path of electrons in th gas in a discharge tube is inversely proportional to the pressure inside it. The Crookes dark space occupies half the length of the discharge tube when the pressure is 0.02 mm of mercury. Estimate the pressure at which the dark space will fill the whole tube.

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Solution

Let the mean free path be L and pressure be P,
Given L \alpha \frac{1}{p} for L = half on th etube length
P = 0.02 mm of Hg.
As 'P' becomes half , L' doubles, that is the whoe tube is filled with crook's dark space
Hence the required pressure
$= \frac{0.02}{2} = 0.01 m o f H g$

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The mean free path of electrons in th gas in a discharge tube is inversely proportional to the pressure inside it. The Crookes dark space occupies half the length of the discharge tube when the pressure is 0.02 mm of mercury. Estimate the pressure at which the dark space will fill the whole tube.

Let the mean free path be L and pressure be P, Given L \alpha \frac{1}{p} for L = half on th etube length P = 0.02 mm of Hg. As 'P' becomes half , L' doubles, that is the whoe tube is filled with crook's dark space Hence the required pressure =0.022=0.01mofHg

Let the mean free path be L and pressure be P,
Given L \alpha \frac{1}{p} for L = half on th etube length
P = 0.02 mm of Hg.
As 'P' becomes half , L' doubles, that is the whoe tube is filled with crook's dark space
Hence the required pressure
$= \frac{0.02}{2} = 0.01 m o f H g$