A-LevelPhysicsElectric fieldsOct/Nov 2019Paper 1 Q101 Mark
A positively charged oil droplet falls in air in a uniform electric field that is vertically upwards. The droplet has a constant terminal speed v₀ and the electric field strength is E. The magnitude of the force due to air resistance acting on the droplet is proportional to the speed of the droplet. Which graph shows the variation with E of v₀?
AGraph of v₀ against E, showing a straight line with negative gradient.
BGraph of v₀ against E, showing a curve with negative gradient that approaches the E-axis asymptotically.
CGraph of v₀ against E, showing a curve with positive gradient that approaches a constant v₀ value asymptotically.
DGraph of v₀ against E, showing a horizontal line (v₀ is constant).
✓ Correct Answer
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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