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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 2 September 2020, Shift 1, Physics Q15

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

A plane electromagnetic wave, has frequency of 2.0×10102.0\times10^{10} Hz and its energy density is 1.02×10−8 J/m31.02\times10^{-8}\ \mathrm{J/m^{3}} in vacuum. The amplitude of the magnetic field of the wave is close to (14πϵ0=9×109 Nm2C2\frac{1}{4\pi\epsilon_0}=9\times10^{9}\ \frac{\mathrm{Nm^{2}}}{\mathrm{C^{2}}} and speed of light =3×108 ms−1=3\times10^{8}\ \mathrm{ms^{-1}}) :
  1. (1)160 nTOfficial answer
  2. (2)180 nT
  3. (3)190 nT
  4. (4)150 nT

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