Metal sphere A directly touches an uncharged metal sphere B.

Note that both spheres are metals so charges readily move. The spheres come into contact with each other, so the positive sphere will "share some of its positives" with the other sphere.

(In reality, some negative charges from the uncharged sphere are drawn out towards the positive charge which is currently deficient in negative charges; this process lasts until the charges are equally distributed throughout)

Now both spheres are positive - but sphere A will no longer be as positive as before.

Why is A not neutralised tho? How u know it doesnt gain enough electrons to be qualified for neutralisation?

Originally metal A is positively charged, meaning there are many more positive charges than negative charges. Let’s say, 50 to 30.

Metal B is neutral, meaning there are as many positive charges as negative charges. Let’s say, 40 to 40.

When the two spheres come into contact, some of the negative charges move from metal B into metal A. But because they have adjoined as a system, they will try to distribute the negative charges equally throughout the two-metal combination.

But their total number of positive charges continue to exceed their total number of negative charges. If I use the numbers above, that’s 90 to 70.

As such, they will evenly distribute the charges around and both will remain positive overall. With the numbers, this is 45 to 35 for each sphere.

But it is also possible for A to gain sufficient electrons to become neutralised overall. What is so unique about this qn that makes A STILL positive?

If A gains the many negative charges, B will be very positive.

A connected system will work its way to an overall well spread-out system of charges. Even if A gains charges momentarily, B will kind of absorb the negative charges.

You won’t be able to have a two-metal connected system with differing charges because negative charges from both spheres can move around the entire system.

No extra electron from outside the spheres can come into the system. This makes A and B positive - but A’s positiveness is weakened because of the absorption of some negative charges.

In short, there will be a system imbalance if A becomes negative.

In my previous example with a total of 90 positive and 70 negative charges, the whole system has a net +20 count of positive charges.

If A is forced to become negative, B will become very positive to keep the whole system count +20. But this is imbalanced - and then the electrons will move around again until both share the distribution.

An analogy is the current budget situation during the COVID period. Businesses suffer while the government has a surplus of budget.

Do you remember that the government provided $320 million help to the tourism sector in the form of rediscover vouchers? [Applies for adults over age 18, so if you ask any of them they should know]

Even as the government provides the help to alleviate the issues, the government does not simply give out all of their resources become “in the negative” in the pursuit of boosting the tourism industry. Having the government giving out the resources is like forcing sphere A to become negative - which isn’t exactly going to be logical.

I get ur idea very much sir.
Thank u for taking the time to explain.
But the qn states “ they are separated afterwards”. Cant i just use this idea to assume that both are positively charged hence the repulsion?

So sorry, I missed the separated portion.

Normally when they are separated, they do not actually have sufficient time to “react”.

Imagine a group of friends, with equal number of girls and boys. Suddenly, a K-pop band comes. Somehow, the group are amazed by the K-pop band then the K-pop band joins the group of friends, talking to one another.

Suddenly, there is an earthquake splitting the ground into two equal parts. By the time everyone recognises this, it becomes too late - the group gets separated into two sections, with some of the group members and some of the K-pop members on one side and the remaining on the other half. There would be no time for the K-pop members to regroup themselves as everything comes in a flash.

This is actually what happens for charges - the charges themselves “are unaware” that the sphere are going to be split.

Your idea of separation is correct - if the spheres are left alone to meddle their own affairs after touching, they are going to repel each other.

Though I believe by “separated” here the question is trying to say “manual separation by a human”.

Okk understand alr ty