The induced current stops when the magnetic field stops changing (i.e. when it has reached full strength), and the needle returns to zero. It remains there until the magnetic field changes again.

They found that constant delivery of these alternating electric fields at a low intensity and an intermediate frequency of 100-300 kilohertz­ — or 100,000 to 300,000 changes in the current direction ...

When an electric field is applied, the strain induced on the BaTiO3 substrate is transferred to the nanoparticles forcing their realignment along a common direction, known as superferromagnetism.

Technical Terms Electroconvection: The process by which an applied electric field induces convective flow and pattern formation through the movement of charge carriers in a liquid crystal.