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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumConceptual

JEE Main 3 September 2020, Shift 2, Physics Q15

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

The electric field of a plane electromagnetic wave propagating along the xx direction in vacuum is E⃗=E0 j^cos⁡(ωt−kx)\vec{E} = E_0\,\hat{j}\cos(\omega t - kx). The magnetic field B⃗\vec{B}, at the moment t = 0 is :
  1. (1)B⃗=E0μ0ϵ0 cos⁡(kx) k^\vec{B} = E_0\sqrt{\mu_0\epsilon_0}\,\cos(kx)\,\hat{k}Official answer
  2. (2)B⃗=E0μ0ϵ0cos⁡(kx) k^\vec{B} = \frac{E_0}{\sqrt{\mu_0\epsilon_0}}\cos(kx)\,\hat{k}
  3. (3)B⃗=E0μ0ϵ0 cos⁡(kx) j^\vec{B} = E_0\sqrt{\mu_0\epsilon_0}\,\cos(kx)\,\hat{j}
  4. (4)B⃗=E0μ0ϵ0cos⁡(kx) j^\vec{B} = \frac{E_0}{\sqrt{\mu_0\epsilon_0}}\cos(kx)\,\hat{j}

Official answer

Option 1

NTA final key (Sep 2020).

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