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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 2 September 2020, Shift 1, Physics Q17

Question 17 of 75 in this shift, Physics question 17 of 25.

Interference fringes are observed on a screen by illuminating two thin slits 1 mm apart with a light source (λ=632.8\lambda=632.8 nm). The distance between the screen and the slits is 100 cm. If a bright fringe is observed on a screen at a distance of 1.27 mm from the central bright fringe, then the path difference between the waves, which are reaching this point from the slits is close to :
  1. (1)1.27 μm1.27\ \mu\mathrm{m}Official answer
  2. (2)2.872.87 nm
  3. (3)2 nm
  4. (4)2.05 μm2.05\ \mu\mathrm{m}

Official answer

Option 1

NTA final key (Sep 2020).

Chapter
Wave Optics
Topic
Young's Double Slit
Idea tested
Position of nth Fringe

Same topic in other shifts

All Young's Double Slit questions
  1. 2 Apr 2026, Shift 2 · Q46In a Young's double slit experiment, the intensity at some point on the screen is found to be 34\frac{3}{4} times of the maximum of the…MediumNumerical value
  2. 4 Apr 2026, Shift 2 · Q50In a double slit experiment, when one of the slits is covered by a transparent mica sheet of refractive index 1.56, the central fringe…MediumNumerical value
  3. 5 Apr 2026, Shift 1 · Q39In Young's double slit experiment, the fringe width of the interference pattern produced on the screen is 2.4 μ2.4\ \mum. If the experiment…EasySingle correct
  4. 5 Apr 2026, Shift 2 · Q42The maximum intensity in a Young's double slit experiment is I0I_0. Distance between the slits (dd) is 5λ5\lambda, where λ\lambda is the…MediumSingle correct
  5. 6 Apr 2026, Shift 1 · Q36In interference experiment the path difference between two interfering waves at a point AA on the screen is λ/3\lambda/3, where λ\lambda…EasySingle correct
  6. 6 Apr 2026, Shift 2 · Q45In a Young double slit experiment, the wavelength of incident light is 6000 Å, the separation between slits S1S_1 and S2S_2 is 5 cm and…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 42 of the 174 JEE Main shifts held from 2017 to 2026.