Final answer:
To determine the magnetic field strength at a point outside a cylindrical tube carrying electric current, we can use principles from physics, specifically Ampère's Law or Biot-Savart Law. The strength of the field is related to the current carried and will diminish with increasing distance from the wire; practical applications require very large currents and fields.
Step-by-step explanation:
The question asked by the student involves calculating the magnetic field strength at a point outside a cylindrical tube carrying an electric current. The situation described is akin to that of a long straight current-carrying wire, for which the magnetic field strength can be calculated using the Ampère's Law or the Biot-Savart Law. While the question does not provide all the details needed for a specific answer (such as the distance from the wire or the current's exact distribution within the tube), these laws of physics suggest that the strength of the magnetic field will decrease with distance from the current source and will be proportional to the current carried by the wire.
An important consideration in real-world applications such as magnetohydrodynamic (MHD) drives is that practical use requires very large currents and magnetic fields to produce significant forces.