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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 6 September 2020, Shift 2, Physics Q16

Question 16 of 75 in this shift, Physics question 16 of 25.

For a plane electromagnetic wave, the magnetic field at a point xx and time t is B⃗(x,t)=[1.2×10−7sin⁡(0.5×103x+1.5×1011t)k^]T\vec{B}(x,t)=\left[1.2\times10^{-7}\sin(0.5\times10^{3}x+1.5\times10^{11}t)\hat{k}\right]\mathrm{T} The instantaneous electric field E⃗\vec{E} corresponding to B⃗\vec{B} is : (speed of light c=3×108 ms−1c=3\times10^{8}\,\mathrm{ms^{-1}})
  1. (1)E⃗(x,t)=[36sin⁡(1×103x+0.5×1011t)j^]Vm\vec{E}(x,t)=\left[36\sin(1\times10^{3}x+0.5\times10^{11}t)\hat{j}\right]\frac{\mathrm{V}}{\mathrm{m}}
  2. (2)E⃗(x,t)=[−36sin⁡(0.5×103x+1.5×1011t)j^]Vm\vec{E}(x,t)=\left[-36\sin(0.5\times10^{3}x+1.5\times10^{11}t)\hat{j}\right]\frac{\mathrm{V}}{\mathrm{m}}Official answer
  3. (3)E⃗(x,t)=[36sin⁡(1×103x+1.5×1011t)i^]Vm\vec{E}(x,t)=\left[36\sin(1\times10^{3}x+1.5\times10^{11}t)\hat{i}\right]\frac{\mathrm{V}}{\mathrm{m}}
  4. (4)E⃗(x,t)=[36sin⁡(0.5×103x+1.5×1011t)k^]Vm\vec{E}(x,t)=\left[36\sin(0.5\times10^{3}x+1.5\times10^{11}t)\hat{k}\right]\frac{\mathrm{V}}{\mathrm{m}}

Official answer

Option 2

NTA final key (Sep 2020).

Topic
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Idea tested
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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.