How can you charge a metal sphere negatively without touching it?

Electric field of an isolated charged metallic sphere at any interior point is

How can we charge two metallic spheres with equal and opposite charge using the method of induction?

There is a metal object A connected to the earth with the help of a connecting wire. A positively charged object B is brought nearer to A without touching it Which of the following statement is correct?

A conductor A is given a charge of amount +Q and then placed inside a deep metal can B , without touching it

Metal sol is negatively charged.

Two isolated metal spheres are identical. They are electrically neutral and are touching. An electrically charged rod is then brought near the spheres without touching them, as the drawing shows. After a while, with the rod held in place, the spheres are separated, and teh rod is then removed. The following statements refere to the mases m_(A) and m_(B) of the spheres after they are separated and the rod is removed. Which of the follownig statements is true?