Circuits

When cells were first invented the theory of electron flow mentioned above was unknown. Rather it was incorrectly assumed that the movement was from the positive to negative terminal.
The electron from the negative terminal is already negatively charged and acts as the destination for the positive terminal. This is called the “Coventional Current Flow”.

Then there are 2 main types of circuits; the series and parallel circuit.
For details see below.

Series Circuits:
-The electrical current through each component is the same, as all the current has to flow through everything in the circuit. When there is only one path you can go through, you have to face all the challenges along that path.

-The potential difference across each component adds up to the potential difference across the battery. This is because the energy transferred from the battery to the electrons must equal the amount of energy transferred by the electrons to the components; otherwise the components would fail to operate at maximum capacity.

- The total resistance across the components in series is equal to the sum of each resistance across the components. The potential difference is largest across the component with the greatest resistance as more energy is transferred by the electrons to overcome the resistance.

Parallel Circuits:
- The total current through the whole circuit is the sum of the current through each electrical component. The current in a parallel circuit branches out after leaving the battery and recombines before entering back in.

- The potential difference across each component is the same. Somehow.

-The combined resistance across the components in parallel is less than either of the separate resistance across the components.


Reference material:
http://www.passmyexams.co.uk/GCSE/physics/conventional-current-series-circuit-parallel-circuit.html