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JEE Main 2024 (5 Apr, Shift 1) · Force on Current-Carrying Conductors

Force on Current-Carrying Conductors question from JEE Main 2024 (5 Apr, Shift 1)

Q21JEE Main 2024 · 5 APR · SHIFT 1Medium

Force on Current-Carrying Conductors

A 2A current carrying straight metal wire of resistance 1 Ω1\ \Omega, resistivity 2×10−6 Ω m2 \times 10^{-6}\ \Omega\text{ m}, area of cross- section 10 mm210\text{ mm}^2 and mass 500 g500\text{ g} is suspended horizontally in mid air by applying a uniform magnetic field B⃗\vec{B}. The magnitude of B is ________ ×10−1 T\times 10^{-1}\text{ T} (given, g=10 m/s2g = 10\text{ m/s}^2).

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

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Answer: 5

  1. Length of the wire: R=ρLA⇒L=RAρ=1×10×10−62×10−6=5 mR = \frac{\rho L}{A} \Rightarrow L = \frac{RA}{\rho} = \frac{1\times10\times10^{-6}}{2\times10^{-6}} = 5\text{ m}
  2. Suspended in air: ILB=mgILB = mg
  3. B=0.5×102×5=0.5 T=5×10−1 TB = \frac{0.5\times10}{2\times5} = 0.5\text{ T} = 5\times10^{-1}\text{ T}
  4. So the answer is 5.
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