1. 10⁵ A/m ² 2. 10⁴ A/m ² 3. 10⁶ A/m ² 4. 10⁻⁵ A/m ²

Answer: 1. 10⁵ A/m ² Current density is J=σ E=E/ρ , so first find resistivity from R=ρ L/A . A=π r²=π·dfrac10⁻⁴π=10⁻⁴\ m² ρ=RA/L=dfrac10×10⁻⁴10=10⁻⁴\ Ωm J=E/ρ=dfrac1010⁻⁴=10⁵\ A/m² . Option (1).

Topic: Resistivity, conductivity and temperature dependence of resistance· Current Electricity

A copper wire of length 10 m and radius (10^-2/√(π)) m has electrical resistance of 10 Ω. The current density in the wire for an electric field strength of 10 (V/m) is :

1. \(10^{5}\) A/m\(^2\)

2. \(10^{4}\) A/m\(^2\)

3. \(10^{6}\) A/m\(^2\)

4. \(10^{-5}\) A/m\(^2\)

Doubtly Asked 30 Oct 2026 NEET UG 2022 Practice test neet Save WhatsApp Report

1 answer

Best answer

Answer: 1. \(10^{5}\) A/m\(^2\)

Current density is \(J=\sigma E=E/\rho\), so first find resistivity from \(R=\rho L/A\).

\(A=\pi r^2=\pi\cdot\dfrac{10^{-4}}{\pi}=10^{-4}\ \text{m}^2\)

\(\rho=\dfrac{RA}{L}=\dfrac{10\times10^{-4}}{10}=10^{-4}\ \Omega\text{m}\)

\(J=\dfrac{E}{\rho}=\dfrac{10}{10^{-4}}=10^{5}\ \text{A/m}^2\). Option (1).

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

Was this answer helpful?

A copper wire of length 10 m and radius (10^-2/√(π)) m has electrical resistance of 10 Ω. The current density in the wire for an electric field strength of 10 (V/m) is :

1 answer

Your answer