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A current density of 2.5 A m⁻² is found to exist in a conductor when an electric field of 5×10⁻⁸ V m⁻¹ is applied across it. The resistivity of the conductor is .........

Asked in RS Academy GUJCET booklet · Ohm's law and resistivity

Answer: (2) 2×10⁻⁸ Ω m

Step-by-step solution

Given: j = 2.5 A m⁻², E = 5×10⁻⁸ V m⁻¹.

Idea: Ohm's law in its microscopic form is E = ρ j, so ρ = E/j.

ρ = (5×10⁻⁸)/(2.5) = 2×10⁻⁸ Ω m.

Units: V m⁻¹ divided by A m⁻² is V A⁻¹ m, that is Ω m.

Why the other options are wrong

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