Two identical wires have the same fundamental frequency of 400 Hz. when kept under the same tension. If the tension in one wire is increased by 2% the number of beats produced will be

(1) 4

(2) 2

(3) 8

(4) 1

(1) $n\propto \sqrt{T}$$\frac{\Delta n}{n}=\frac{1}{2}\frac{\Delta T}{T}$

Beat frequency $=\Delta n=\left(\frac{1}{2}\frac{\Delta T}{T}\right)n=\frac{1}{2}×\frac{2}{100}×400=4$

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