Power source, connectors and load.
complex circuit
meow
parallel
Battery, switch, wires, lightbulb, etc. Those are SOME parts of a circuit....
An electric current flowed around the circuit.
when he connected the parts he got an electric current.
Cannot say without seeing the circuit.
wire diagram and list of parts for Solar electric fence
The parts in an electric circuit are as follows: wires that contain two D-cells, a light bulb, and a switch, the D-cells are the energy source, the bulb is the load, the switch controls the flow of electric charges and the connecting wires provide a complete path that joins all the parts together.
Transistor, resistor, diode, output.
An electric circuit is a system of several parts. The circuit cannot function without all of them therefore there is no 'main' part. Essential parts are; power source, conducting material, load.
Since we cannot see the picture... we cannot help you !