JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 26 February 2021, Shift 1, Physics Q24

Question 24 of 90 in this shift, Physics question 24 of 30, Section B.

The mass per unit length of a uniform wire is 0.135 g/cm. A transverse wave of the form

y=-0.21\sin(x+30t)

is produced in it, where

x

is in meter and t is in second. Then, the expected value of tension in the wire is

x\times10^{-2}

N. Value of

x

is __________. (Round-off to the nearest integer)

Official answer

1215

NTA final key.

Chapter: Waves
Topic: Waves on Strings
Idea tested: Wave Speed on String

Same idea in other shifts

Asked 9× in all

8 Apr 2025, Shift 2 · Q34Two strings with circular cross section and made of same material, are stretched to have same amount of tension. A transverse wave is then…EasySingle correct
10 Apr 2023, Shift 1 · Q52A transverse harmonic wave on a string is given by $y(x,t) = 5\sin(6t + 0.003\,x)$ where $x$ and $y$ are in cm and $t$ in sec. The wave…EasyNumerical value
11 Apr 2023, Shift 2 · Q51A wire of density $8\times10^{3}\ \mathrm{kg/m^3}$ is stretched between two clamps $0.5\ \mathrm{m}$ apart. The extension developed in the…MediumNumerical value
15 Apr 2023, Shift 1 · Q51The fundamental frequency of vibration of a string stretched between two rigid support is 50 Hz. The mass of the string is 18 g and its…EasyNumerical value
28 Jul 2022, Shift 1 · Q39In the wave equation $y=0.5\sin\frac{2\pi}{\lambda}(400\,t-x)\ \mathrm{m}$ the velocity of the wave will be :EasySingle correct
29 Jul 2022, Shift 2 · Q56The speed of a transverse wave passing through a string of length 50 cm and mass 10 g is 60 $\mathrm{ms^{-1}}$ . The area of cross-section…MediumNumerical value
25 Feb 2021, Shift 2 · Q23The percentage increase in the speed of transverse waves produced in a stretched string if the tension is increased by 4%, will be…EasyNumerical value
8 Jan 2020, Shift 2 · Q9A transverse wave travels on a taut steel wire with a velocity of $v$ when tension in it is $2.06\times10^{4}\ \mathrm{N}$ . When the…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.