My uncle is a judge in the circuit court. This requires him to travel to diffferent locations to ensure wide visibility and understanding of cases within a region
That's cool!  What does a judge in the circuit court do?
He just has to travel a lot to make sure there is a wide visibility of the cases. Back in the days, the judges actually traveled on horseback! 
How large of an area does he have to travel?  Just within a single city, county, state or nation wide?
I believe it is within a broad area within a state. Most circuit courts have actually been replaced by judges that are regularly stationed.
Do you know who the first appointed circuit court judge was?
Assize of Clarendon). Thus, the term "circuit court" is derived from the practice of having judges ride around the countryside each year on pre-set paths − circuits − to hear cases. Especially on the United States frontier, a judge might travel on horseback along with a group of lawyers. Abraham Lincoln was one such attorney who would ride the circuit in Illinois. In more settled areas, a stagecoach would be used. Eventually, the legal caseload in a county would become great enough to warrant the establishment
Circuit court
Circuit courts are court systems in several common law jurisdictions. The core concept of circuit courts requires judges to travel to different locales to ensure wide visibility and understanding of cases in a region. More generally, some modern circuit courts may also refer to a court that merely holds trials for cases of multiple locations in some rotation.
History.
King Henry II instituted the custom of having judges ride the circuit each year to hear cases, rather than requiring every citizen to bring their cases to London (see