Quantisation of Charge
Electric charge exists in discrete packets, being an integral multiple of the elementary charge 'e'.
What is Quantisation of Charge?
The principle that electric charge exists only in discrete amounts, which are integer multiples of the elementary charge 'e'.
Key formula / rule: Quantisation of Charge
Key points
- Understand that electric charge is quantised.
- Apply the formula q = n*e to calculate charges.
- Differentiate between quantised and continuous charge distribution.
Common exam trap
Assuming charge can be any real number (continuous).
Definitions
- Term
Quantisation of Charge
- Meaning
The principle that electric charge exists only in discrete amounts, which are integer multiples of the elementary charge 'e'.
- Term
Elementary Charge (e)
- Meaning
The magnitude of the electric charge carried by a single electron or proton, approximately 1.602 x 10-19 Coulombs.
- Term
Quantum of Charge
- Meaning
The smallest possible unit of electric charge that can exist independently, which is the elementary charge 'e'.
Learning objectives
Understand that electric charge is quantised.
Apply the formula q = n*e to calculate charges.
Differentiate between quantised and continuous charge distribution.
Formulae
- Name
Quantisation of Charge
- Note
q is the total charge, n is an integer (number of elementary charges), and e is the magnitude of the elementary charge (charge of an electron or proton).
- Expression
q = n*e
Prerequisites
Basic understanding of electric charge.
Concept of elementary particles (electrons, protons).
Common mistakes
Assuming charge can be any real number (continuous).
Forgetting that 'n' must be an integer.
Confusing the magnitude of 'e' with the total charge.
Not considering the sign of the charge (positive or negative).
Keywords
Quantisation of Charge
Elementary Charge
Integer Multiple
Coulomb
Electron
Proton
Discrete Charge
Practice preview
If an object has a net charge of +2e, how many electrons have been removed from it?…
easy
Which of the following statements about the quantisation of charge is INCORRECT?…
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What is the smallest unit of electric charge that can be isolated?…
easy