A block diagram is a simple drawing depicting the components of a system and the connections between them using single lines and abstract symbols rather than realistic images. Block diagrams are used in schematic diagrams and electrical plans to represent various devices in a circuit through standardized pictograms.

2.  It shows a picture or sketch of the
various components of a specific
system and the wiring between these
components.

4. It has only single line that
represent its connection.

5. a representation of the elements of a
system using abstract, graphic symbols
rather than realistic pictures.

8. are small drawings or pictograms used to
represent various electrical devices in a
diagram or plan of an electrical circuit.
 used in sketching schematic diagrams and
electrical plans for numerous types of electrical
works.