Shunt (electrical) called a "crowbar" as it is likened to dropping an actual crowbar across a set of bus bars (exposed electrical conductors). An ammeter shunt allows the measurement of current values too large to be directly measured by a particular ammeter. In this case the shunt, a manganin resistor of accurately known resistance, is placed in parallel with the moving coil galvanometer, thus all of the current to be measured will flow through it. In order not to disrupt the circuit, the resistance of the shunt is normally very low. The voltage drop across the shunt is proportional to the current
Electrical telegraph Electrical telegraph An electrical telegraph is a telegraph that uses electrical signals, usually conveyed via dedicated telecommunication circuit or radio. The electrical telegraph, or more commonly just telegraph, superseded optical semaphore telegraph systems, thus becoming the first form of electrical telecommunications. In a matter of decades after their creation in the 1830s, electrical telegraph networks permitted people and commerce to transmit messages across both continents and oceans almost instantly, with widespread social and economic impacts. From early studies of electricity, electrical phenomena were known to travel with great speed, and many experimenters worked on the application of electricity to communications