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Electric Current

Problem 3.214

The air between two closely located plates is uniformly ionized by ultraviolet radiation. The air volume between the plates is equal to V=500 cm3V=500 \mathrm{~cm}^{3}, the observed saturation current is equal to Isat=0.48μI_{s a t}=0.48 \mu A. Find: (a) the number of ion pairs produced in a unit volume per unit time; (b) the equilibrium concentration of ion pairs if the recombination coefficient for air ions is equal to r=1.67⋅10−6 cm3/sr=1.67 \cdot 10^{-6} \mathrm{~cm}^{3} / \mathrm{s}

Reveal Answer
3.214. (a) n˙i=Isat /eV=6⋅109 cm−3⋅s−1;\dot{n}_{i}=I_{\text {sat }} / e V=6 \cdot 10^{9} \mathrm{~cm}^{-3} \cdot \mathrm{s}^{-1} ; (b) n=ni/r=n=\sqrt{n_{i} / r}= =6⋅107 cm−3=6 \cdot 10^{7} \mathrm{~cm}^{-3}
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