InterviewSolution
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InterviewSolution
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Fig. reprensts a crystal unit of cesuim chloride, CsCl. The cesium atoms, represented by open circles are situated at the corners fo a cubeof side 0.40 mm, whereasa CI atom us situated at the centers of the cube. The Cs atoms are deficient in one electron while the CI atom carriesan excess electron. (i) What is the net electric field on the CI atom due to eightCs atoms ? (ii) Suppose that the Cs atom at the cornerA is missing. What is the net forcenow on the CI atom due to sevenremaning Cs atoms ? |
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Answer» Solution :(i) Fig, Chiloine atom at the center of the CUBE is attractedequally by eightcesiumatoms at the eightcorners of the cubeSymmetry showsthat theseforceswouldcancelout in PAIRS. Therefore, net ELECTRICFIELD on CI atm dueto eightCs atoms is zero. (ii) Removing a Cs atom at the cornerA is equivalentto addinga singlychargednegative Cs ion at A. Net force on the CIatom at A would be `F = (e^(2))/(4PI in_(0) r^(2))`, where r = distancebetween CI iion and Cs ion, i.e, `r = sqrt((0.20)^(2) + (0.20)^(2) + (0.20)^(2)) xx 10^(-9) m = 0.346xx10^(-9) m` `F = (e^(2))/(4pi in_(0) r^(2)) = (9xx10^(9) (1.6xx10^(-19))^(2))/((0.346xx10^(-9))^(2)) = 1.92xx10^(-9) N` 
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