Physics
Conductivity is a measure of how easily electric charges can move through a material and is expressed in units of siemens per meter. There are two main types of conductivity: electrolytic conductivity, which pertains to the ability of ions to conduct current in a solution, and metallic conductivity, which refers to the ability of free electrons to conduct current in a metal.
Conversely, resistivity, represented by the Greek letter rho (ρ) and measured in ohm-meters, quantifies how much a material resists the flow of current. Resistivity is influenced by the density of free electrons and is generally the same for any two samples of a given material. Furthermore, it is also affected by temperature, with higher temperatures generally causing increased resistivity. An object's resistance, on the other hand, depends not only on resistivity but also on its size and shape and can be quantified by the equation: resistance (R) = resistivity (ρ) x length (L) / cross-sectional area (A). Finally, a resistor is a circuit element made of a material with intermediate resistivity, and its symbol in circuit diagrams is a zigzag-shaped line.
Lesson Outline
<ul> <li>Conductivity <ul> <li>Defined as the measure of how easily electric charges can move through a material, expressed in units of siemens per meter (S/m)</li> <li>Types of conductivity: <ul> <li>Electrolytic conductivity pertains to the ability of ions to conduct current in a solution</li> <li>Metallic conductivity refers to the ability of free electrons to conduct current in a metal</li> </ul> </li> </ul> </li> <li>Resistivity <ul> <li>Defined as the property that quantifies how much a material resists the flow of electric current, represented by the Greek letter rho (ρ) and measured in ohm-meters (Ω•m)</li> <li>Low resistivity pertains to conductors, and high resistivity pertains to insulators</li> <li>Resistivity is influenced by the density of free electrons in a material and can change with temperature; typically, higher temperatures cause increased resistivity</li> </ul> </li> <li>Resistance <ul> <li>Defined as the opposition to the flow of electric current in a material, symbolized by (R), and its units are ohms (Ω)</li> <li>Dependent not only on a material's resistivity but also on its size and shape, quantified by the equation: Resistance (R) = Resistivity (ρ) x Length (L) / Cross-Sectional Area (A)</li> </ul> </li> <li>Resistors <ul> <li>Defined as a circuit element made of a material with intermediate resistivity, which is used to limit or regulate the flow of electrical current in a circuit</li> <li>Symbolized in circuit diagrams as a zigzag-shaped line</li> </ul> </li> </ul>
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FAQs
Conductivity is the ability of a material to conduct electric current, whereas resistivity is the inherent property of a material that opposes the flow of electric current. Conductivity is the inverse of resistivity. Typically, materials with high conductivity and low resistivity are good conductors of electricity, while materials with low conductivity and high resistivity are considered insulators.
Electrolytic conductivity is the ability of ions in an electrolyte solution to carry an electric charge. This type of conductivity depends on ion concentration, mobility, and charge. On the other hand, metallic conductivity is the ability of metals to conduct an electric charge through the movement of electrons. Metallic conductivity arises from the delocalized nature of electrons in metals, forming an "electron sea" that can easily move and carry current throughout the metallic lattice.
Ohm-meters (Ω·m) are the units used to represent resistivity. Ohm-meter is derived from combining Ohms (Ω), which are units of resistance, and meter (m), representing the length of the conducting material. Resistivity is calculated by multiplying the resistance of a material with its cross-sectional area and dividing by its length. Consequently, resistivity expressed in ohm-meters allows for direct comparison between different materials' ability to oppose the flow of electric current, regardless of their dimensions.
Temperature has a significant impact on resistance and resistivity. In general, as the temperature increases, so does the resistance of the material. This occurs because higher temperatures cause atoms within the material to vibrate more, increasing the incidence of electron collisions and thus impeding the flow of current. For most metals, resistivity increases as temperature increases, while for semiconductors, resistivity generally decreases as temperature increases, leading to an increase in conductivity.
