2.4.77 - E.m.f. and internal resistance

Know the definition of electromotive force (e.m.f.) and understand what is meant by internal resistance and know how to distinguish between e.m.f. and terminal potential difference.

Use - e.m.f. and internal resistance to connect the rule to the data and decision in the question.

This matters because - e.m.f. and internal resistance determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - e.m.f. and internal resistance to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - E.m.f. and internal resistance is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.