Maths And Physics With Pandey Sir NCERT 12th Physics Chapter-14 Classification of Metals, Conductors and Semiconductors

# Classification of Metals, Conductors and Semiconductors

Contents

On the basis of the relative values of electrical conductivity(σ) and resistivity(ρ=1/σ), the solid are broadly classified as

### 1. Metals

They have very low resistivity or high conductivity.

Resistivity ρ ≈ 10⁻² – 10⁻⁸ Ωm  and Conductivity σ = 10²  – 10⁸ S/m (Siemens/metre)

### 2. Insulators

They have high resistivity or low conductivity.

Resistivity ρ ≈ 10¹¹ – 10¹⁹ Ωm  and  Conductivity σ = 10⁻¹¹  – 10⁻¹⁹ S/m (Siemens/metre)

### 3. Semiconductors

They have resistivity or conductivity intermediate to metals and insulators.

Resistivity ρ ≈ 10⁻⁵ – 10⁶ Ωm  and Conductivity σ = 10⁵  – 10⁻⁶ S/m (Siemens/metre)

In this chapter we will study of Semiconductors, which can be following types.

#### (I) Element Semiconductors

These Semiconductors are available in natural form.

Exp – Silicon (Si) and Germanium (Ge)

#### (II) Compound Semiconductors

These semiconductors are made by compounding the metals.

Exp – (a) Inorganic Semiconductors are CDs, GaAs, CdSe, InP etc.

(b) Organic polymer are polypyrrole, polyaniline, etc.