Final answer:
Giant planets have stronger magnetic fields than terrestrial planets due to electric currents created by their rapid spin, which produce large magnetospheres.
Step-by-step explanation:
The magnetic fields of giant planets are generally stronger than those of terrestrial planets. This strength is due to the electric currents generated by the rapid spinning of a giant planet's interior, which creates vast magnetospheres that can extend millions of kilometers into space. In contrast, terrestrial planets, like Earth, have comparatively weaker magnetic fields and smaller magnetospheres. Jupiter is known to have the strongest magnetic field among the planets in the Solar System, which contributes to its large magnetosphere.