Electrical resistivity

Definition

Electrical resistivity is a fundamental property of materials that quantifies how strongly a given material opposes the flow of electric current. It is influenced by factors such as temperature, impurities, and structural defects in the crystal lattice, which can lead to disorder that affects conductivity. Understanding electrical resistivity is crucial for analyzing how thermal vibrations and occupational disorder in crystals alter the movement of charge carriers within the material.

5 Must Know Facts For Your Next Test

1. Electrical resistivity is typically measured in ohm-meters (Ω·m) and varies significantly across different materials, with metals generally having low resistivity and insulators high resistivity.
2. The resistivity of materials increases with temperature due to increased thermal vibrations, which create more scattering events for charge carriers.
3. Impurities and defects in the crystal lattice can significantly affect electrical resistivity; even small amounts of foreign atoms can disrupt the orderly arrangement of atoms and increase resistance.
4. For semiconductors, resistivity can be modified through doping, where specific impurities are introduced to enhance or reduce charge carrier concentration.
5. The Hall effect can be used to measure electrical resistivity indirectly by applying a magnetic field perpendicular to the current flow and measuring the induced voltage across the material.

Review Questions

• How do thermal vibrations affect electrical resistivity in crystalline materials?
  • Thermal vibrations play a significant role in determining electrical resistivity because as temperature increases, atoms within the crystal lattice vibrate more vigorously. This increased motion leads to more frequent collisions between charge carriers (like electrons) and vibrating atoms, which hinders their movement. Consequently, this results in an increase in electrical resistivity as the material becomes less conductive at higher temperatures.
• Discuss how occupational disorder can influence the electrical properties of crystals.
  • Occupational disorder refers to imperfections in a crystal's atomic arrangement where some atoms occupy non-ideal positions. This disorder disrupts the orderly flow of electrons or other charge carriers through the material. When charge carriers encounter these disruptions, they scatter more often, which increases resistance and thus raises the electrical resistivity of the crystal. Therefore, higher levels of occupational disorder lead to poorer electrical conductivity in crystalline materials.
• Evaluate the impact of impurities on the electrical resistivity of semiconductor materials and how this relates to their applications in technology.
  • Impurities have a profound impact on the electrical resistivity of semiconductor materials because they alter the concentration and type of charge carriers present. Doping semiconductors with specific impurities introduces either excess electrons (n-type) or creates holes (p-type), allowing for better control over conductivity. This manipulation of electrical resistivity is essential for various applications in technology, including transistors, diodes, and photovoltaic cells, as it enables tailored electronic properties for optimal performance in devices.

Related terms

conductivity: Conductivity is the reciprocal of resistivity, measuring a material's ability to conduct electric current, with higher conductivity indicating lower resistivity.

thermal vibrations:

Thermal vibrations refer to the oscillations of atoms in a crystal lattice due to temperature changes, which can influence the mobility of charge carriers and hence the electrical resistivity.

occupational disorder:

Occupational disorder describes a condition in a crystal where atoms are not arranged in their ideal positions, leading to increased scattering of charge carriers and higher electrical resistivity.