Beats are produced by waves $\mathrm{y}_1=\mathrm{a} \sin 2000 \pi \mathrm{t}$ and $\mathrm{y}_2=\mathrm{a}…

Beats are produced by waves $\mathrm{y}_1=\mathrm{a} \sin 2000 \pi \mathrm{t}$ and $\mathrm{y}_2=\mathrm{a} \sin 2008 \pi \mathrm{t}$. The number of beats heard per second is
  1. 4
  2. 1
  3. zero
  4. 8

Solution

$\begin{array}{ll}2 \pi \mathrm{n}_1=2000 \pi & \therefore \mathrm{n}_1=1000 \mathrm{~Hz} \\ 2 \pi \mathrm{n}_2=2008 \pi & \therefore \mathrm{n}_2=1004 \mathrm{~Hz} \\ \text { Beat frequency }=\mathrm{n}_2-\mathrm{n}_1=4 \mathrm{~Hz}\end{array}$

Asked in: MHT CET 2021 (20 Sep Shift 1)

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