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Question
Answer the following question:
Find the expression for the resistivity of a material.
Solution
Resistance R of a conductor depends on the length 'l' and area of cross-section 'A' of the conductor.
R α l
and R α `(1)/("A")`
∴ `"R" ∝ "l"/"A"`,
∴ R = `"Q" xx ("l")/("A")` ( Q is constant)
Q ( Resistivity) = `("RA")/("l")`
Where Q (rho) is called resistivity of the conductor it is also called as specific resistance.
If we put L = 1m and A = 1m2 then R = Q
Conclusion
Thus, the resistivity of a conductor is defined as the resistance of a conductor of unit length and unit area of cross-section. The SI units of resistivity are ohm-meter ( Ω - m).
Resistivity is the characteristics property of a material. It is a different material.
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