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Friday, 9 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumConceptual

JEE Main 25 July 2021, Shift 1, Physics Q10

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

A linearly polarized electromagnetic wave in vacuum is E=3.1cos⁡[(1.8)z−(5.4×106)t]i^E=3.1\cos\left[(1.8)z-\left(5.4\times10^6\right)t\right]\hat{i} N/C is incident normally on a perfectly reflecting wall at z=az=a. Choose the correct option
  1. (1)The frequency of electromagnetic wave is 54×10454\times10^4 Hz.
  2. (2)The reflected wave will be 3.1cos⁡[(1.8)z+(5.4×106)t]i^3.1\cos\left[(1.8)z+\left(5.4\times10^6\right)t\right]\hat{i} N/COfficial answer
  3. (3)The transmitted wave will be 3.1cos⁡[(1.8)z−(5.4×106)t]i^3.1\cos\left[(1.8)z-\left(5.4\times10^6\right)t\right]\hat{i} N/C
  4. (4)The wavelength is 5.4 m

Official answer

Option 2

NTA final key.

Chapter
Electromagnetic Waves
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.