A-LevelPhysicsElectric fieldsOct/Nov 2009Paper 1 Q271 Mark
The diagram shows two parallel horizontal metal plates held at a potential difference V. [Figure 27.1] A small charged liquid drop, midway between the plates, is held in equilibrium by the combination of its weight and the electric force acting on it. The acceleration of free fall is g and the electric field strength is E. What is the ratio of the charge to mass of the drop, and the polarity of the charge on the drop?
Acharge/mass: g/E, polarity: positive
Bcharge/mass: g/E, polarity: negative
Ccharge/mass: E/g, polarity: positive
Dcharge/mass: E/g, polarity: negative
✓ Correct Answer
The correct answer is B: charge/mass: g/E, polarity: negative
📋 Examiner Report & Trap Analysis
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...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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