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Question
Difference between resistance and resistivity?
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Solution
ohm(Ω)
Resistivity is a characteristic property of the material. It is a measure of material's ability to oppose electric current. Its SI unit is Ω−m (ohm - meter).
Resistivity depends on the nature of the material, not on its dimensions as resistance.
Resistance(R)=ρlength(l)area(A)
Where ρ=resistivity
Resistance is the electric property that impedes a current. A current flowing through a wire (or resistor) is like water flowing through a pipe, and the voltage drop across the wire is like the pressure drop which pushes water through the pipe. Resistance is proportional to how much pressure is required to achieve a given flow, while conductance is proportional to how much flow occurs for a given pressure. Conductance and resistance are reciprocals. The resistance of an object depends on its shape and the material of which it is composed. The cylindrical resistor is easy to analyze, and by doing so we can gain insight into the resistance of more complicated shapes. As you might expect, the cylinder's electric resistance R is directly proportional to its length L, similar to the resistance of a pipe to fluid flow. The longer the cylinder, the more collisions charges will make with its atoms. The greater the diameter of the cylinder, the more current it can carry (again, similar to the flow of fluid through a pipe). In fact, R is inversely proportional to the cylinder's cross-sectional area A.
As mentioned, for a given shape, the resistance depends on the material of which the object is composed. Different materials offer different resistance to the flow of charge. We define the resistivity ρ of a substance so that the resistance of an object is directly proportional to ρ. Resistivity ρ is an intrinsic property of a material, independent of its shape or size. In contrast, the resistance R is an extrinsic property that does depend on the size and shape of the resistor. Recall that an object whose resistance is proportional to the voltage and current is known as a resistor.
Resistivity is a characteristic property of the material. It is a measure of material's ability to oppose electric current. Its SI unit is Ω−m (ohm - meter).
Resistivity depends on the nature of the material, not on its dimensions as resistance.
Resistance(R)=ρlength(l)area(A)
Where ρ=resistivity
Resistance is the electric property that impedes a current. A current flowing through a wire (or resistor) is like water flowing through a pipe, and the voltage drop across the wire is like the pressure drop which pushes water through the pipe. Resistance is proportional to how much pressure is required to achieve a given flow, while conductance is proportional to how much flow occurs for a given pressure. Conductance and resistance are reciprocals. The resistance of an object depends on its shape and the material of which it is composed. The cylindrical resistor is easy to analyze, and by doing so we can gain insight into the resistance of more complicated shapes. As you might expect, the cylinder's electric resistance R is directly proportional to its length L, similar to the resistance of a pipe to fluid flow. The longer the cylinder, the more collisions charges will make with its atoms. The greater the diameter of the cylinder, the more current it can carry (again, similar to the flow of fluid through a pipe). In fact, R is inversely proportional to the cylinder's cross-sectional area A.
As mentioned, for a given shape, the resistance depends on the material of which the object is composed. Different materials offer different resistance to the flow of charge. We define the resistivity ρ of a substance so that the resistance of an object is directly proportional to ρ. Resistivity ρ is an intrinsic property of a material, independent of its shape or size. In contrast, the resistance R is an extrinsic property that does depend on the size and shape of the resistor. Recall that an object whose resistance is proportional to the voltage and current is known as a resistor.
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