JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 8 January 2020, Shift 1, Physics Q15

Question 15 of 75 in this shift, Physics question 15 of 25, Section A.

The critical angle of a medium for a specific wavelength, if the medium has relative permittivity 3 and relative permeability

\frac{4}{3}

for this wavelength, will be :

(1) $30^\circ$ Official answer
(2) $45^\circ$
(3) $60^\circ$
(4) $15^\circ$

Official answer

Option 1

NTA final key (Jan 2020).

Chapter: Ray Optics and Optical Instruments
Topic: Refraction and Snell's Law
Idea tested: Total Internal Reflection

Same idea in other shifts

Asked 6× in all

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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 42 of the 174 JEE Main shifts held from 2017 to 2026.