That force is produced by an electromagnetic actuator. [Grady] scratch-built his watt-balance from wood, however, even though he carefully turned and wound his own coils for the electromagnets ...

Of the four known fundamental forces of nature, the weak nuclear force is the one with the least obvious purpose. Gravity holds stars together and keeps us on the ground. The electromagnetic force ...

Now, the kilogram is defined in relation to the Planck constant, the smallest amount of energy a photon can carry. With this constant, scientists can make ultra-precise mass measurements using the ...