While I'm working on the Magical Artillery, let's look at another common spell.
Mage Light is a very handy invention. When cast, the spell creates an orb, 13 cm in diameter. The orb radiates white light, usually between 30-50 candelas in luminous intensity, though it can be decreased or increased at the mage's convenience, but brighter lights dim sooner.
The orb is very lightweight and lukewarm or warm to the touch. While it can last quite long, if its light begins to dim, a special fluid has to be poured into the orb to slowly restore its brightness to the preferred level.
Also, the orb can hover around people. It usually has an orbit (preset by the caster) that it tries to follow. However, it’s easy to detach or stop them; you can do it with one to three fingers.
The spell requires a very tiny amount of material components (not counting the fluid that it uses).
Magic is actually ancient technology in this world. Given that and the info above, how can my Mage Light actually work?