Physics - Wave on String Question with Solution | TestHub

Fundamental frequency of wire A, $f_A=256$ Hz

Fundamental frequency of wire B, $f_B=382$ Hz

Frequency of the third harmonic of A, $f_1=3f_A=3\times 256=768$ Hz

Frequency of the second harmonic of B, $f_2=2f_B=2\times 382=764$ Hz

Beat frequency, $n=|f_1-f_2|=|768-764|=4$ Hz

Number of beats heard in one second is $4$.

Number of beats heard in two seconds is $4\times 2=8$.