Class 12 Physics
CBSE and UP Board
Current Electricity
Exercise 3
Chapter-3 Exercise 3.6
A negligibly small current is passed through a wire of length 15 m and uniform cross-section 6.0 × 10⁻⁷ m² , and its resistance is measured to be 5.0 Ω. What is the resistivity of the material at the temperature of the experiment?
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Length of the wire, l =15 m
Area of cross-section of the wire, a = 6.0 x 10⁻7 m2, Resistance of the material of the wire, R = 5.0Ω. Resistivity of the material of the wire = ρ, Resistance is related with the resistivity as
R = ρ l /A
=> ρ = RA/l
= 5 x 6.0 x 10⁻7 / 15 = 2x 10⁻7 Ωm
Therefore, the resistivity of the material is 2 x 10_7Ωm.