Explain Millikan’s oil drop experiment and how it led to the measurement of the electron’s charge. Why is the magnitude of the charge of the electron so important?

Solution : The diagram consists of doubly charged cation(red sph eres) and two singly charged anions(blue spheres) thus charge is balanced. The given diagram contains 12 blue spheres and 6 red spheres. Here, the number of cations (red spheres) = 6 the number of anions (blue spheres) =12 The ratio of cations to anions = 6: 12 = 1: 2 (reduced to simplest form). Among the given formulas only Ca(N0 ) satisfies th3 2 e ratio and others i.e, KBr is in the ratio 1:1, K S0 is in the ratio 2:1, Fe (S0 ) i s in the ratio 2:3. 2 4 2 4 3 Hence the formula Ca(N0 ) is con3 2nt with the diagram. Name of the compound is : Calcium nitrate. It is made of 1 atom of Calcium(Ca) and 2 atoms of Nitrate( N0 ) ion. 3