Anonymous
Anonymous asked in Science & MathematicsPhysics · 1 decade ago

What is an ultrasonic wave? / 53 kHz to 91 kHz Estimate the wavelengths in air of these frequencies.?

a) What is an ultrasonic wave?

b) The pipistrelle bat emits sound waves in the range 53 kHz to 91 kHz.

Estimate the wavelengths in air of these frequencies.

c) Why is a very short wavelength of benefit to bats?

many thanks for your help!!

Pepe

2 Answers

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  • 1 decade ago
    Best Answer

    a) High frequency short wave length sound waves which are not audible to human ear. Their frequency is greater than 20 kHz

    b) Taking the velocity of sound in air as v = 340 m/s, wave length range is λ = 340/53x10^3 = 6.4x10^-3 m

    to

    340/91x10^3 = 3.73x10^-3 m

    c) They can travel long distances as a sharp beam. Bats can listen to the reflected waves from obstacles in front of them , react immediately and move without hitting the obstacles.

  • 1 decade ago

    a)

    An ultrasonic wave is a wave that the tympanic membrane cannot use, the frequency is higher than audible human hearing above 16k to 20k Hz.

    b)

    The speed of sound is approx 340 m/s, frequency x wavelength = speed so work it out, divide 340 by the frequency to give wavelength.

    c)

    Mammalian retinas have rod photoreceptors for night vision and cone photoreceptors for daylight and colour vision. For colour discrimination, most mammals possess two cone populations with two visual pigments (opsins) that have absorption maxima at short wavelengths (S, blue or ultraviolet) and long wavelengths (L, green or red).

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