Operating Principles of the NIST 4 Watt Balance Source

The video tutorial explains the concept of balancing forces, comparing gravitational and electromagnetic methods. It introduces the Watt balance, a device that measures mass indirectly by determining the strength of a magnetic field and the current through a coil. The Watt balance operates in two modes: velocity mode, which measures field strength, and weighing mode, which balances the weight of a test mass using electromagnetic force. NIST's design uses a wheel instead of a balance beam, with laser sensors and interferometry ensuring precise measurements.

What is the primary function of a Watt balance?

Describe the two measuring modes of the Watt balance.

How does the Velocity Mode of the Watt balance work?

Explain the process that occurs in the Weighing Mode of the Watt balance.

What role do laser sensors play in the operation of the Watt balance?