Q.What is the principle of conservation of charge?
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Basic Properties and Conservation of Electric Charge
Electric charge is a fundamental scalar property of matter, carried by protons (+e) and electrons (-e), that adds algebraically (additivity: the net charge on any body is simply the signed sum of all the charge it contains) and obeys a strict conservation law: the total charge of an isolated system -- and of the universe as a whole -- can never change, only be transferred or redistributed between objects. Rubbing two neutral objects together (triboelectric charging) does not create new charge; it merely transfers existing electrons from one object's atoms to the other's, leaving one object with a surplus of electrons (net negative) and the other with a deficit (net positive), while the sum of the two charges remains exactly zero throughout, since both started neutral. This conservation law was established historically by Benjamin Franklin from experiments with rubbed rubber and glass rods, and it ranks alongside conservation of …
The behaviour of charge during processes like friction or particle reactions is governed by a fundamental conservation law, much like conservation of energy or momentum. …
Conservation of charge: total charge of an isolated system is constant — charge is neither created nor destroyed.
The principle of conservation of charge states that:
The total electric charge of an isolated system always remains constant. Electric charge can neither be created nor destroyed; it can only be transferred from one body to another.
- When a glass rod is rubbed with silk, the rod loses electrons and the silk gains an equal amount — the net charge of the rod–silk system stays zero. …
- CBSE 2026Set ANNUAL1 markMCQQ.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. When you comb in dry hairs it gets charged due to?(a) Friction(b) Conduction(c) Induction(d) Grounding
›Reveal solutionSolution
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 …
- CBSE 2026Set ANNUAL1 markMCQQ.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. Which part of atom physically manipulated in this type of electrification?(a) Protons(b) Electrons(c) Nucleus(d) Neutrons
›Reveal solutionSolution
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 …
- CBSE 2026Set ANNUAL1 markMCQQ.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:(a) Double(b) Equal(c) Half(d) Four times
›Reveal solutionSolution
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 …
- CBSE 2026Set ANNUAL1 markQ.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. 3 balls K, L & M have charged 1 C, 3 C and 4 C respectively. The ball K is first brought into contact with L and then M. Find the final charge on M. OR Why we observe electric shock on touching a metallic door handle after moving on the floor with carpet?
›Reveal solutionSolution
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 qK=1C, qL=3C share equally (identical spheres):
qK=qL=21+3=2C each
Step 2 — K (now 2 C) touches M (4 C): …
- CBSE 2019Set ANNUAL1 markQ.Process of sharing the charges with the earth is called as ____________ .
›Reveal solutionSolution
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 …
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