The new definition of the kilogram in terms of Planck's constant

Abstract

In 2019, the unity of mass of the International System of Units (SI), the kilogram, will have its definition modified. It will not be anymore the metallic artifact kept in the BIPM building, in the neighborhood of Paris, to be based on Planck's constant (h). What is the need for this change? And how the measurements will be done? These are some of the questions that will be answered at this communication, where we describe the operation of the experiment named Watt Balance used in the new way to realize the unity of mass. Besides that, we will describe how we assembled a Balance for teaching purposes, used in talks about the theme. The topic interests everybody, but in special students that take physics courses in any area.