Specific resistance, also known as resistivity, is a material property that quantifies how strongly a material opposes the flow of electric current.
What is the unit of specific resistance in the SI system?
The unit of specific resistance in the SI system is ohm-meter (Ω·m).
How is specific resistance related to conductivity?
Specific resistance is the reciprocal of conductivity, meaning if resistivity increases, conductivity decreases and vice versa.
What factors affect the specific resistance of a material?
The specific resistance of a material is affected by temperature, material composition, and impurities.
What is the formula for calculating specific resistance?
The formula for specific resistance is ρ = RA/L, where ρ is resistivity, R is resistance, A is cross-sectional area, and L is length.
Why do metals usually have low specific resistance?
Metals have low specific resistance due to their free-moving electrons, which facilitate the easy flow of electric current.
How does specific resistance change with temperature in conductors?
In conductors, specific resistance generally increases with temperature.
How does specific resistance change with temperature in semiconductors?
In semiconductors, specific resistance decreases with increasing temperature.
What is the difference between specific resistance and resistance?
Resistance is a property of an object, while specific resistance is a material property per unit length and cross-section.
Can specific resistance be negative?
No, specific resistance cannot be negative; it is a positive quantity representing energy dissipation in a material.
How is specific resistance measured experimentally?
Specific resistance is measured by determining the resistance of a material sample, then using its dimensions in ρ = RA/L.
What are the typical specific resistance values for metals?
Metals typically have specific resistance values on the order of 10^-8 to 10^-6 Ω·m.
What kind of materials have high specific resistance?
Insulators such as rubber, glass, and ceramics have high specific resistance, often greater than 10^10 Ω·m.
Why is specific resistance important in selecting materials for electrical components?
Specific resistance helps determine the most efficient and practical materials for specific electrical applications, balancing cost, performance, and durability.
In what type of application would a high specific resistance material be preferred?
High specific resistance materials are preferred in insulation for cables and electronic devices to prevent accidental electrical flow.