The ratio of magnetic fields on the axis of a circular current carrying coil of radius \(a\) to the magnetic field at its centre will be

• Correct answer
  A

  \(\frac{1}{\left(1+\frac{x^2}{a^2}\right)^{3 / 2}}\)
• B

  \(\frac{1}{\left(1+\frac{a^2}{x^2}\right)^{1 / 2}}\)
• C

  \(\frac{1}{\left(1+\frac{a^2}{x^2}\right)^2}\)
• D

  \(\frac{1}{\left(1+\frac{a^2}{x^2}\right)^3}\)

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