A current of 45 A is passing through an infinitely long wire which lies along the axis of an infinitely long solenoid of radius 1 cm. The magnetic field produced by the solenoid in the direction of the current in the wire is 4 mT. What is the approximate magnitude of the resultant magnetic field at a point 3 mm radially away from the solenoid axis? (Use \(\mu_o=4 \pi \times 10^{-7} \mathrm{~T} \mathrm{~m} / \mathrm{A}\).)

• Correct answer
  A

  5 mT
• B

  1 mT
• C

  7 mT
• D

  3 mT

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