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JEE Main 2019 (10 Apr, Shift 1) · Electric Current, Drift Velocity & Current Density

Electric Current, Drift Velocity & Current Density question from JEE Main 2019 (10 Apr, Shift 1)

Q29JEE Main 2019 · 10 APR · SHIFT 1Medium

Electric Current, Drift Velocity & Current Density

A current of 5 A passes through a copper conductor (resistivity = 1.7 × 10–8 Ω\Omegam) of radius of cross- section 5 mm. Find the mobility of the charges if their drift velocity is 1.1 × 10–3 m/s.

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Answer: (b)

  1. J=Iπr2=5π×25×10−6≈6.37×104 A/m2J = \dfrac{I}{\pi r^{2}} = \dfrac{5}{\pi \times 25 \times 10^{-6}} \approx 6.37 \times 10^{4}\text{ A/m}^{2}
  2. E=ρJ=1.7×10−8×6.37×104≈1.08×10−3 V/mE = \rho J = 1.7 \times 10^{-8} \times 6.37 \times 10^{4} \approx 1.08 \times 10^{-3}\text{ V/m}
  3. μ=vdE=1.1×10−31.08×10−3≈1.0 m2/Vs\mu = \dfrac{v_d}{E} = \dfrac{1.1 \times 10^{-3}}{1.08 \times 10^{-3}} \approx 1.0\text{ m}^{2}\text{/Vs}
  4. So the answer is (b).
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