A-LevelPhysicsD.C. circuitsOct/Nov 2019Paper 1 Q341 Mark
Two cells with electromotive forces E₁ and E₂ and internal resistances r₁ and r₂ are connected to a resistor R as shown. [Figure showing two cells E₁ with r₁ and E₂ with r₂ connected in series with an external resistor R, with a current arrow.] The terminal potential difference across cell 1 is zero. Which expression gives the resistance of resistor R?
A(E₂r₁ − E₁r₂) / E₁
B(E₂r₁ − E₁r₂) / E₂
C(E₁r₂ − E₂r₁) / E₁
D(E₁r₂ − E₂r₁) / E₂
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The correct answer is A. This question tests the candidate's understanding of d.c. circuits within the Physicssyllabus. The examiner's mark scheme requires...
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Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
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