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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumConceptual

JEE Main 25 February 2021, Shift 2, Physics Q10

Question 10 of 90 in this shift, Physics question 10 of 30, Section A.

An electron with kinetic energy K1K_1 enters between parallel plates of a capacitor at an angle ‘α\alpha’ with the plates. It leaves the plates at angle ‘β\beta’ with kinetic energy K2K_2. Then the ratio of kinetic energies K1:K2K_1 : K_2 will be :
  1. (1)cos⁡βcos⁡α\frac{\cos\beta}{\cos\alpha}
  2. (2)cos⁡βsin⁡α\frac{\cos\beta}{\sin\alpha}
  3. (3)sin⁡2βcos⁡2α\frac{\sin^2\beta}{\cos^2\alpha}
  4. (4)cos⁡2βcos⁡2α\frac{\cos^2\beta}{\cos^2\alpha}Official answer

Official answer

Option 4

NTA final key.

Chapter
Electrostatic Potential and Capacitance
Topic
Electric Field
Idea tested
Charged Particle Trajectory in Uniform Field

Same idea in other shifts

Asked 3× in all
  1. 29 Jun 2022, Shift 1 · Q48A positive charge particle of 100 mg is thrown in opposite direction to a uniform electric field of strength…EasySingle correct
  2. 8 Jan 2020, Shift 2 · Q13A particle of mass m and charge q is released from rest in a uniform electric field. If there is no other force on the particle, the…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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.