Final answer:
A circuit with all parts connected in a single loop is a series circuit, which has a single path for current flow and the total resistance is the sum of all resistors in the loop.
Step-by-step explanation:
A circuit in which all parts are connected in a single loop is called a series circuit. In a series circuit, components such as resistors are connected end-to-end, providing a single path for current flow.
This is in contrast to a parallel circuit, where components are connected across common points, providing multiple paths for current flow.
The total resistance of a series circuit is the sum of the individual resistances of each component, as there is only one path for electrons to flow through.
Series circuits are often represented in schematics by a battery (depicted as two parallel red lines), conducting wires (represented as straight lines), and the load (such as a resistor, depicted as a zigzag).
An example can be seen in Figure 20.3 which represents a wide variety of similar circuits. An important characteristic of a series circuit is that if one component fails, the entire circuit is interrupted, as the single path is broken.