Zheng Jie's answer to Liew Zhen jie's Junior College 2 H1 Maths Singapore question.

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Zheng Jie
Zheng Jie's answer
15 answers (Tutor Details)
1st
Emf = e - ir where r is internal resistance. When circuit is closed, there charge carriers need to pass through the extra resistance, leading to energy loss in the battery. Hence minus ir