2.4.68 - Combining resistances in series and parallel

Be able to derive the equations for combining resistances in series and parallel using the principles of charge and energy conservation, and be able to use these equations.

Use - combining resistances in series and parallel to connect the rule to the data and decision in the question.

This matters because - combining resistances in series and parallel determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - combining resistances in series and parallel to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Combining resistances in series and parallel is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.