Final answer:
The device that contacts the third rail to power train motors is called a collector shoe. It is essential for drawing electrical power directly from the rail, enabling continuous energy supply to trains without the need for onboard batteries.
Step-by-step explanation:
The device that contacts the third rail to transmit power to train motors is known as a shoe or collector shoe. It is a sliding contact that draws electrical power from the third rail, which is an additional rail beside the main tracks supplying electric power to trains. When trains utilize overhead wires instead, a different device called a pantograph is used.
Electric rail systems often employ this type of power delivery for efficient and constant energy supply. Unlike vehicles which require batteries, trains can receive continuous power from either the third rail or overhead wires, thereby reducing the need for onboard energy storage. This system can be seen in various light rail systems and high-speed trains.
Applying principles of electromagnetic induction, electric trains are an excellent example of converting electrical energy into mechanical energy, which is used to propel the train. The armature, often found within motors, plays a critical role in this energy conversion.