what is a soucer circuit? what is a sinker circuit? and their applications?

Answer 1

A source circuit supplies current. An example would be a battery. It "sources" electrons. Of course every source circuit must have a branch to supply the current and one for return.

A sink circuit uses current. Any load would be an example, such as a light bulb. Some loads can have current run through them in either direction, and some can have current run in only one direction.

Sources supply currents for sinks.