A-LevelPhysicsElectric fieldsMay/June 2020Paper 1 Q321 Mark
A charged oil droplet of mass m is falling, initially freely, in a vacuum between two horizontal metal plates that are separated by a distance x. A potential difference (p.d.) V is then applied across the plates. This results in the oil droplet continuing to accelerate downwards but with a reduced acceleration a. The polarity of the applied p.d. is then reversed so that the direction of the electric force on the droplet is reversed. This results in the downwards acceleration of the oil droplet increasing to 3a. What is the magnitude of the charge on the oil droplet?
Amgx / V
B2mgx / V
C3mgx / V
D4mgx / V
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The correct answer is A. This question tests the candidate's understanding of electric fields 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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