Frequency Physics Example 4

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Example 4

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A guitar string vibrates at a fundamental frequency of 330 Hz330 \text{ Hz}. What are the frequencies of the second and third harmonics? If the string length is 0.65 m0.65 \text{ m}, what is the wavelength of the fundamental?

Solution

  1. 1
    Harmonics are integer multiples of the fundamental: 2nd harmonic = 2×330=660 Hz2 \times 330 = 660 \text{ Hz}. 3rd harmonic = 3×330=990 Hz3 \times 330 = 990 \text{ Hz}.
  2. 2
    For a string fixed at both ends, the fundamental wavelength is twice the string length: λ1=2L=2×0.65=1.30 m\lambda_1 = 2L = 2 \times 0.65 = 1.30 \text{ m}.

Answer

f2=660 Hz,  f3=990 Hz,  λ1=1.30 mf_2 = 660 \text{ Hz}, \; f_3 = 990 \text{ Hz}, \; \lambda_1 = 1.30 \text{ m}
A vibrating string produces a fundamental and harmonics (overtones). The fundamental has one antinode; each higher harmonic adds another antinode, shortening the wavelength and increasing the frequency by integer multiples.

About Frequency

The number of complete wave cycles passing a fixed point per second, measured in hertz (Hz).

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