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JEE Main 2013 (25 Apr, Shift 1) · Applications of Dimensional Analysis

Applications of Dimensional Analysis question from JEE Main 2013 (25 Apr, Shift 1)

Q75JEE Main 2013 · 25 APR · SHIFT 1Medium

Applications of Dimensional Analysis

A metal sample carrying a current along X-axis with density JxJ_x is subjected to a magnetic field BzB_z (along z-axis). The electric field EyE_y developed along Y-axis is directly proportional to JxJ_x as well as BzB_z. The constant of proportionality has SI unit.

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Answer: (b)

  1. Ey=R JxBzE_y = R\,J_xB_z, so R=EJBR = \dfrac{E}{JB}.
  2. Units: EE in V/m == kg m s−3^{-3}A−1^{-1}, JJ in A m−2^{-2}, BB in T == kg s−2^{-2}A−1^{-1}.
  3. JBJB = kg m−2^{-2}s−2^{-2}, so RR = kg m s−3A−1kg m−2s−2=\dfrac{\text{kg m s}^{-3}\text{A}^{-1}}{\text{kg m}^{-2}\text{s}^{-2}} = m3^3 s−1^{-1}A−1^{-1}.
  4. So the answer is (b) m3As\dfrac{m^3}{As}.
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