When there is no method of sending information to the final control element, what type of system is it?

An open loop system is characterized by the absence of feedback. In this type of system, the input is processed to produce an output without any adjustments based on the output's performance. Essentially, once the command is issued, the system operates independently of the controlled variable's state. Since there is no provision to send information back to modify or adjust the system's operation, it cannot correct errors or respond to changes in the system's environment.

This structure is typically simpler and less expensive than systems with feedback, but it may not be suitable for all applications, especially where precise control is necessary. An example of an open loop system is a basic electric heater, where the heater operates for a set duration without monitoring the actual temperature achieved.