"The Natural Philosopher" wrote in message
...
More concealed elements and more accurate scales to heat less water

totally pointless. Existing kettle can heat less than a cup of wtaer.

Depends on the area of the base of the kettle and the height of the top of
the element above the base. If the kettle is a small diameter and has an
element that rises only a few mm above the base, less depth of water is
needed to cover the element and the depth amounts to less volume, compared
with an ancient kettle with a very wide base and an element that stands a
long way off the bottom.

Comparison between a modern jug kettle and my parents' first (early 1960s)
kettle with the handle on the top rather than the side, a very wide, squat
design and an element where the *bottom* of it was about 1 cm above the base
of the kettle and the top was a good 2 cm above that because the element was
curved at the ends/sides and not flat.