Q73 / 90 · JEE Main 2021 (20 Jul Shift 1) · Physics

A current of 5 A is passing through a non-linear magnesium wire of cross-section 0.04 m2. At every point the direction of current density is at an angle of 60° with the unit vector of area of cross-section.
The magnitude of electric field at every point of the conductor is: (resistivity of magnesium ρ=44×10-8 Ωm)

  • A
    11×10-2 V m-1
  • B
    11×10-7 V m-1
  • Correct answer
    C
    11×10-5 V m-1
  • D
    11×10-3 V m-1

Solution

I=J→·A→=JAcos(θ)
5=J4100×cos(60)
J=5×50=250 A m-2
Now, E→=ρ×J→
=44×10-8×250=11×10-5 V m-1

Hence, the correct answer is option: 'C'.

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