I've learnt about conductivity and molar conductivity in school.
I know that conductivity is the conductance of a solution of unit volume/ of unit cross-sectional area and distance between the electrodes.
The book then goes on to say "we must define a more useful quantity called Molar Conductivity."
How is Λm more useful than κ? Though Λm=κ/c, both κ and Λm vary with concentration. What is the use of defining Λm if it varies (though in an opposite manner) like κ?
And a related question: I know that Λm increases with dilution (more ionic mobility), and that κ decreases with dilution as there are less ions per unit volume. But wouldn't more ions per unit volume decrease conductivity, as it does with Λm due to interactions between the ions?