What is the name of a judges hammer?

Answer 1

It is called a gavel.

here is some more info

A gavel is a small ceremonial mallet commonly made of hardwood, typically fashioned with a handle and often struck against a sound block to enhance its sounding qualities. It is used by presiding officers---notably American judges, chairmen, and auctioneers---to call for attention or to punctuate rulings and proclamations. It is customarily struck to indicate the opening and closing of proceedings, giving rise to the phrase "gavel-to-gavel" to describe the entirety of a meeting or session. Robert's Rules of Order provides guidelines on the proper use of the gavel in deliberative assemblies.

By metonymy, the gavel represents the entire judiciary system, especially of judgeship; to "bring down the gavel" means to enforce or compel with the power of a court. It also represents the authority of presiding officers; thus the expression "passing the gavel" signifies an orderly succession from one chair to another.

The origin of the gavel's use, indeed of the word itself, is uncertain; in Middle English it refers to rent or tribute paid to a lord. It is possible that the use of a hammer in legislative or judiciary proceedings may represent Mjolnir, the hammer of Thor, as the use of lawspeakers at Thing (assembly) is a practice that originated in heathen Scandinavia. Masonic organizations used the maul as a symbol as early as the 18th century, through which the hammer may have come to represent meetings and order. Another theory posits that the word is related to the gable of a roof, whose shape may resemble a mallet or gavel.

The image of the gavel is often used erroneously by advertising agencies worldwide to signify legal proceedings in many different jurisdictions, such as England & Wales, where in fact the gavel is never used.