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If electronic charge e , electron mass m , speed of light in vacuum c and Planck's constant h are taken as fundamental quantities, the permeability of vacuum μ 0 can be expressed in units of:

Options

  1. Am c 2 h e 2
  2. Bh m e 2
  3. Ch c m e 2
  4. Dh c e 2

Correct answer

D. h c e 2

Step-by-step solution

Magnetic potential energy inside a solenoid is U = 1 2 L I 2 Where L = self-inductor ⇒ U = 1 2 μ 0 n 2 A   l I 2 ∵ n = number of turns per unit length = N l U = 1 2 μ 0 N l 2 A l   I 2 U = 1 2 μ 0 N 2 l 2 A l   I 2   μ 0 = 2 U l N 2 A I 2 Dimensionally, U = h c λ I = e T A = l 2 l = l ′ μ 0 = h c λ   [ l ] l 2 t 2 e 2 = h λ t e 2 = h c e 2 μ 0 = h c e 2

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