Standard kilogram
device · 1889 · Electric age
A platinum–iridium cylinder; since 2019 defined through the Planck constant.
What it is made of
- Platinum-iridium cylinder — has part. A 39 × 39 mm cylinder.
- Glass bell jars — has part. Three caps protect against contamination.
Principles and materials it uses
- Platinum — is made of. A platinum–iridium alloy.
- Metric system — uses. The unit of mass.