JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 4 August 2021, Shift 2, Physics Q11

Question 11 of 90 in this shift, Physics question 11 of 30, Section A.

The tension in a string is increased by 44%. If its frequency of vibration is to remain unchanged, its length must be increased by

(1)12%
(2)20%Official answer
(3)24%
(4)56%

Official answer

Option 2

NTA final key.

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

Same idea in other shifts

Asked 6× in all

5 Apr 2024, Shift 2 · Q55A sonometer wire of resonating length 90 cm has a fundamental frequency of 400 Hz when kept under some tension. The resonating length of…EasyNumerical value
8 Apr 2023, Shift 2 · Q51A guitar string of length 90 cm vibrates with a fundamental frequency of 120 Hz. The length of the string producing a fundamental…EasyNumerical value
13 Apr 2023, Shift 2 · Q54In an experiment with sonometer when a mass of 180 g is attached to the string, it vibrates with fundamental frequency of 30 Hz. When a…EasyNumerical value
9 Jan 2020, Shift 2 · Q11A 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…MediumSingle correct
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 108 of the 174 JEE Main shifts held from 2017 to 2026.