Conductors and Insulators
Materials classified based on their ability to allow electric charges to move freely through them.
What is Conductors and Insulators?
A material that allows electric charges to flow through it easily due to the presence of free electrons.
Key formula / rule: Electrical Conductivity
Key points
- Define conductors and insulators.
- Explain the microscopic basis for conductivity and insulation.
- Identify common examples of conductors and insulators.
- Understand the concept of electrical conductivity and resistivity.
Common exam trap
Confusing conductors and semiconductors.
Definitions
- Term
Conductor
- Meaning
A material that allows electric charges to flow through it easily due to the presence of free electrons.
- Term
Insulator
- Meaning
A material that strongly opposes the flow of electric charge due to electrons being tightly bound to atoms.
- Term
Electrical Conductivity (σ)
- Meaning
A measure of a material's ability to conduct electric current.
- Term
Electrical Resistivity (ρ)
- Meaning
A measure of a material's opposition to the flow of electric current.
Learning objectives
Define conductors and insulators.
Explain the microscopic basis for conductivity and insulation.
Identify common examples of conductors and insulators.
Understand the concept of electrical conductivity and resistivity.
Formulae
- Name
Electrical Conductivity
- Note
σ is conductivity, ρ is resistivity. High σ means good conductor; low σ means good insulator.
- Expression
\σ = \frac{1}{\ρ}
Prerequisites
Basic atomic structure (electrons, nucleus)
Concept of electric charge
Electric field
Common mistakes
Confusing conductors and semiconductors.
Assuming all non-metals are perfect insulators.
Overlooking the role of impurities in water's conductivity.
Not understanding that conductivity is a spectrum, not a binary state.
Keywords
Conductor
Insulator
Electric charge
Free electrons
Bound electrons
Conductivity
Resistivity
Metals
Non-metals
Semiconductor
Practice preview
A material that has very few free electrons and offers significant resistance to the flow of electric current is known as:…
medium
Which of the following is an example of an electrical insulator?…
easy
Metals are generally good conductors of electricity because:…
easy