Question

Quantisation of charge indicates that

• A. Charge, which is a fraction of charge on an electron, is not possible
• B. A charge cannot be destroyed
• C. Charge exists on particles
• D. There exists a minimum permissible charge on a particle

Hint:

Distinguish between the three fundamental properties of charge: 1. \textbf{Quantisation}: Charge comes in integer multiples of \(e\). (\(Q=ne\)). 2. \textbf{Conservation}: The total charge of an isolated system remains constant. 3. \textbf{Additivity}: The total charge of a system is the algebraic sum of individual charges.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The principle of "quantisation of charge" is a fundamental property of electric charge. It states that electric charge is not continuous but exists in discrete packets.
Step 2: Detailed Explanation:
The principle of quantisation of charge states that the total charge (\(Q\)) on any object is always an integer multiple of a basic unit of charge, denoted by \(e\). This basic unit is the magnitude of the charge of a single electron or proton (\(e \approx 1.602 \times 10^{-19}\) C).
The formula is: \(Q = ne\), where \(n\) is an integer (\(n = 0, \pm 1, \pm 2, \ldots\)).
Let's evaluate the given options based on this principle:
(A) Charge, which is a fraction of charge on an electron, is not possible: This is a direct consequence of the rule \(Q = ne\). Since \(n\) must be an integer, it is impossible for an isolated object to have a charge of, for example, 0.5\(e\) or 1.7\(e\). This statement accurately describes quantisation.
(B) A charge cannot be destroyed: This describes the law of conservation of charge, which is a different principle.
(C) Charge exists on particles: This is a true statement, but it is not the meaning of quantisation.
(D) There exists a minimum permissible charge on a particle: This is also a consequence of quantisation (the minimum non-zero charge is \(e\)), but option (A) is a more complete and precise statement of the principle. It explains *why* there is a minimum charge and also rules out all non-integer multiples, not just those below the minimum.
Step 3: Final Answer:
The most accurate and comprehensive description of the quantisation of charge among the choices is that charge cannot exist as a fraction of the elementary charge \(e\). Therefore, option (A) is the best answer.