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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedMediumDiagram reading

JEE Main 18 March 2021, Shift 2, Physics Q17

Question 17 of 90 in this shift, Physics question 17 of 30, Section A.

Three rays of light, namely red (R), green (G) and blue (B) are incident on the face PQ of a right angled prism PQR as shown in the figure. The refractive indices of the material of the prism for red, green and blue wavelength are 1.27, 1.42 and 1.49 respectively. The colour of the ray(s) emerging out of the face PR is :

The figure, in words

Right-angled triangular prism PQR: P at top, Q at bottom-left with a right-angle mark, R at bottom-right; PQ is the vertical left face, QR the horizontal base, PR the sloping face. Three horizontal arrows from the left, labelled B (top), G (middle) and R (lowest), strike the face PQ.
  1. (1)blue and green
  2. (2)blue
  3. (3)green
  4. (4)redOfficial answer

Official answer

Option 4

NTA final key.

Chapter
Ray Optics and Optical Instruments
Topic
Refraction and Snell's Law
Idea tested
Wavelength Dependence of TIR

Same topic in other shifts

All Refraction and Snell's Law questions
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  6. 7 Apr 2025, Shift 2 · Q42A transparent block A having refractive index μ=1.25\mu=1.25 is surrounded by another medium of refractive index μ=1.0\mu=1.0 as shown in figure.…MediumSingle correctHas 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.