magnet, porcelain
磁 centers on magnetic attraction and the material that exhibits it: a magnet. The porcelain sense is a specific application, referring to porcelain's historical association with magnetic properties or the material itself.
磁 combines 石 (stone) with 兹, which likely contributes the sound. The character originally referred to a type of stone with magnetic properties, later extended to porcelain.
The left side 石 is a stone, and the right side 兹 looks like a tangled magnetic field. Picture a lodestone, a naturally magnetic rock, with invisible lines of force swirling around it.
For ジ, imagine a magnet shaped like the letter G attracting metal objects: G -> ジ, and the stone magnet pulls them in.
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magnetism
electromagnetic
magnet
electromagnetic wave
magnetic field
ceramics; pottery and porcelain
porcelain; china; chinaware
magnetism; magnetic force
magnetism
electromagnetism
clay
electromagnetic field
white porcelain
magnetic field
geomagnetism; terrestrial magnetism
celadon porcelain
magnetization; magnetisation
magnetic storm
electromagnet
magnetic flux