1. Mar 1, 2009

### DIMSKK

1. A certain charge "Q" is to be divided into two parts, "Q-q" and "q". What is the relation of "Q" to "q" if two parts, placed at a given distance apart, are to have the maximum coulomb's repulsion?

I am unable to find the condition when there is a maximum Coulomb's repulsion. Any help will be greatly appreciated.

DIMSKK

2. Mar 1, 2009

What have you tried so far?

3. Mar 1, 2009

### rl.bhat

Write down the expression for the force between the charges. Find the differentiation with respect to q and equate it to zero. That gives you the condition for the maximum coulomb's repulsion.

4. Mar 1, 2009

### DIMSKK

Why find the differentiation with respect to q and then equate it to 0? I mean why force will be maximum when we do this? Can anyone explain? Moreover, whether we differentiate the expression with "Q" or "q"?

Last edited: Mar 1, 2009
5. Mar 1, 2009

### DIMSKK

Now I have found what is the reason. Thank you very much for help rl.bhat.