JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 9 January 2020, Shift 1, Physics Q9

Question 9 of 75 in this shift, Physics question 9 of 25, Section A.

Three harmonic waves having equal frequency

\nu

and same intensity

I_0

, have phase angles

0, \frac{\pi}{4}

and

-\frac{\pi}{4}

respectively. When they are superimposed the intensity of the resultant wave is close to :

(1) $I_0$
(2) $0.2\,I_0$
(3) $3\,I_0$
(4) $5.8\,I_0$ Official answer

Official answer

Option 4

NTA final key (Jan 2020).

Chapter: Waves
Topic: Waves on Strings
Idea tested: Superposition of Traveling Waves

Same idea in other shifts

Asked 3× in all

8 Apr 2025, Shift 2 · Q40The amplitude and phase of a wave that is formed by the superposition of two harmonic travelling waves, $y_1(x, t) = 4\sin(kx - \omega t)$ …MediumSingle correct
26 Aug 2021, Shift 2 · Q30Two waves are simultaneously passing through a string and their equations are : $y_1=\mathrm{A_1}\sin k(x-vt)$ ,…MediumNumerical value

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.