WATT BALANCE PROJECT
Metrologists at the BIPM in Sèvres
near Paris, France, seek to redefine
the kilogram by tying it to the Planck
constant. Once it is finished, their
watt balance will essentially compare
the gravitational force on a mass –
here represented by five copper
weights – with the magnetic force
on a coil in a magnetic field.
The final setup will be placed inside
a vacuum chamber.