JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 9 January 2020, Shift 2, Physics Q11

Question 11 of 75 in this shift, Physics question 11 of 25, Section A.

A wire of length

L

and mass per unit length

6.0\times10^{-3}\ \mathrm{kg\,m^{-1}}

is put under tension of 540 N. Two consecutive frequencies that it resonates at are : 420 Hz and 490 Hz. Then

L

in meters is :

(1)5.1 m
(2)1.1 m
(3)2.1 mOfficial answer
(4)8.1 m

Official answer

Option 3

NTA final key (Jan 2020).

Chapter: Waves
Topic: Waves on Strings
Idea tested: Sonometer Laws

Same idea in other shifts

Asked 4× in all

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2 Sep 2020, Shift 1 · Q10Two identical strings $X$ and $Z$ made of same material have tension $T_X$ and $T_Z$ in them. If their fundamental frequencies are 450 Hz…EasySingle correct

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.