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JEE Main 2021 (24 Feb, Shift 2) · Electric Current, Drift Velocity & Current Density

Electric Current, Drift Velocity & Current Density question from JEE Main 2021 (24 Feb, Shift 2)

Q25JEE Main 2021 · 24 FEB · SHIFT 2Medium

Electric Current, Drift Velocity & Current Density

A cylindrical wire of radius 0.5 mm and conductivity 5 ×\times 107 S/m is subjected to an electric field of 10 mV/m. The expected value of current in the wire will be x3π\pi mA. The value of x is _________.

Numerical answer type. Work it out, then open the answer.

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Answer: 5

  1. J=σE=5×107×10×10−3=5×105 A/m2J = \sigma E = 5 \times 10^{7} \times 10 \times 10^{-3} = 5 \times 10^{5}\text{ A/m}^{2}
  2. A=πr2=π×0.25×10−6 m2A = \pi r^{2} = \pi \times 0.25 \times 10^{-6}\text{ m}^{2}
  3. I=JA=0.125π A=125π mA=53π mAI = JA = 0.125\pi\text{ A} = 125\pi\text{ mA} = 5^{3}\pi\text{ mA}
  4. So x=5x = 5
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