Q31 / 117 · NTA Abhyas (JEE Main) 2020 · Physics · Waves and Sound

There are two waves having wavelength 100  cm and 101  cm and same velocity 303  m s-1. The beat frequency is

  • A
    4  Hz
  • B
    1  Hz
  • Correct answer
    C
    3  Hz
  • D
    2  Hz

Solution

If f1 and f2 are the frequencies (f1>f2) of the two waves, then the beat frequency fb=f1-f2

Frequency of 1st wave,

f1=V1λ1=303100×102=3.03×102 Hz

For 2nd wave, f2=V1λ2=303101×102=3×102 Hz

So, beat frequency =f1-f2

=3.03×102-3×102=.03×102=3 Hz

Hence, the correct answer is option: 'C'.

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