Q.Case study: When a glass rod is rubbed with silk, the rod acquires one type of charge, and the silk acquires the other type of charge. This is true for any pair of objects that are rubbed with each other to be electrified. Now the electrified glass rod is brought in contact with silk cloth, which was rubbed; they no longer attract each other. They also do not repel or attract each other light pieces of paper and other such objects; thus, charges they acquire by rubbing get lost when they come in contact with each other. Positive and negative charge on neutral objects are:

Combing dry hair charges both the comb and hair by friction (triboelectric charging).

When a comb is rubbed against dry hair, electrons transfer from one surface to the other due to rubbing (friction). This leaves the comb and hair with equal and opposite charges — this is charging by friction, the same m …

Frictional charging always involves the transfer of loosely bound outer electrons, never protons or the nucleus.

During charging by friction, only the electrons, being light and loosely bound in the outermost shells of atoms, get transferred from one surface to the other. Protons remain fixed within the nucleus and are never transferred; the object losing electron …

A neutral object has exactly as much positive charge (protons) as negative charge (electrons), so the net charge is zero.

Every atom is built from protons (positive) and electrons (negative). An object is electrically neutral precisely when the total positive charge equals the total negative ch …

When identical conducting spheres touch, charge redistributes equally between them; applying this twice (K–L, then K–M) gives 3 C on M.

Step 1 — K touches L: Charges $q_K = 1\,\text{C}$, $q_L = 3\,\text{C}$ share equally (identical spheres):

$q_K = q_L = \dfrac{1+3}{2} = 2\,\text{C each}$

Step 2 — K (now 2 C) touches M (4 C): …

Connecting a charged body to the earth so that charge flows until the body's potential equals the earth's (taken as zero) is called earthing.

The earth is an enormous conductor, so it behaves like an infinite reservoir of charge — adding or removing charge from it produces no measurable change in its own potential. When a charged conductor is joined to the earth by a conducting wire, charge flows between the conductor and the earth until the potential of …