Question

Why would a magnetohydrodynamic drive work better in ocean water than in fresh water? Also, why would superconducting magnets be desirable?

Short answer

The magnetohydrodynamic drive works better in ocean water than in freshwater because salt water is more conductive and superconducting magnets are more efficient to move fluid. This increases the efficiency.

Step-by-step solution

Magnetohydrodynamic Drive

A magnetohydrodynamic drive also known as MHD accelerator is a method that uses electric and magnetic fields for propelling vehicles with no moving components and by employing magnetohydrodynamics to accelerate an electrically conductive propellant (liquid or gas).

Reason

1. Ocean water is made up of salt water and is more conductive than fresh water.

2. As magnetohydrodynamic drive uses electric and magnetic fields for propelling vehicles; both magnetic and electric fields interact to apply a force to the water which ejects it from the rear of the ship.

3. The force experienced by a charged particle with charge${}^{\mathrm{q}}$, moving in a magnetic field${}^{\mathbf{B}\mathbf{\text{'}}}$with veloci ${}^{\stackrel{\rightharpoondown }{v}}$is,.${}^{\mathbf{F}\mathbf{=}\mathbf{q}\left(\stackrel{\rightharpoondown }{v}\times B\text{'}\right)}$.

4. Superconducting magnets are electromagnets built from coils of superconducting materials or wires.

5. The magnetic field created by such magnets is more intense because superconducting magnets conduct larger electric currents.

6. Hence, in comparison to regular electromagnets, superconducting magnets have lower energy losses.

Therefore, due to the more conductivity of ocean water; magnetohydrodynamic drives work better in ocean water than in fresh water, and to increase overall efficiency superconducting magnets are desirable.