In a reference book, a question was asked to whether three cells of unequal emfs are characterized by a definite emf and internal resistance.
I thought the answer to be in the affirmative. But no, in the book it's given that there is No Formula for calculaing the equivalent emf and equivalent internal resistance of non-similar cells joined in parallel.
But only minutes before I had read the formulae for determining these quantities:
Now, we can easily determine the equivalent end and equivalent internal resistance from these formulae, can we not? So what am I missing?
Is there something wrong with how I interpreted what these formulas mean or what my book really said?
EDIT: The concerned question and the solution are shown below: