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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceDiagram basedMediumMulti-step

JEE Main 2 September 2020, Shift 1, Physics Q11

Question 11 of 75 in this shift, Physics question 11 of 25.

A charged particle (mass mm and charge qq) moves along XX axis with velocity V0V_0. When it passes through the origin it enters a region having uniform electric field E⃗=−Ej^\vec{E}=-E\hat{j} which extends upto x=dx=d. Equation of path of electron in the region x>dx>d is :

The figure, in words

X-Y axes with origin O; particle enters along +X with velocity V0; uniform field E pointing down (-Y) between x=0 and x=d (two vertical lines), no field beyond x=d.
  1. (1)y=qEdmV02 xy=\frac{qEd}{mV_0^{2}}\,x
  2. (2)y=qEd2mV02 xy=\frac{qEd^{2}}{mV_0^{2}}\,x
  3. (3)y=qEdmV02 (x−d)y=\frac{qEd}{mV_0^{2}}\,(x-d)
  4. (4)y=qEdmV02(d2−x)y=\frac{qEd}{mV_0^{2}}\left(\frac{d}{2}-x\right)Official answer

Official answer

Option 4

NTA final key (Sep 2020).

Same idea in other shifts

Asked 2× in all
  1. 2 Sep 2020, Shift 2 · Q3A small point mass carrying some positive charge on it, is released from the edge of a table. There is a uniform electric field in this…MediumDiagram basedHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.