Verified Solution • 2025–26 Session moderate

QJEEM21Ph510b: JEE Main 2021 Physics - Class 12 JEEM21Ph510b Solution: A current of 10A exists in a wire of cross-sectional area of 5…

A current of 10A exists in a wire of cross-sectional area of 5 mm2 with a drift velocity of 2 ×\times 10 −- 3 ms −- 1. The number of free electrons in each cubic meter of the wire is ___________.

Multiple Choice Options

  • A 625 ×\times 1025
  • B 1 ×\times 1023
  • C 2 ×\times 1025
  • D 2 ×\times 106

Step-by-Step Verified Solution

I=neAVdI = neA{V_d}

n=IeAVdn = {I \over {eA{V_d}}}

=101.6×10−9×5×10−6×2×10−3= {{10} \over {1.6 \times {{10}^{ - 9}} \times 5 \times {{10}^{ - 6}} \times 2 \times {{10}^{ - 3}}}}

=102516=6.25×1027=625×1025= {{{{10}^{25}}} \over {16}} = 6.25 \times {10^{27}} = 625 \times {10^{25}}

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