a. An FM radio station broadcasts at a frequency of 101.3 MHz. What is the wavelength?
b. What is the frequency of a sound source that produces the same wavelength in 20°C air?

Respuesta :

Answer:

a) [tex]\lambda = \frac{3x10^8 m/s}{101300000 Hz}= 2.962 m[/tex]

b)  [tex] f= \frac{343 m/s}{2.962 m}= 115.8 Hz[/tex]

Explanation:

For this case we have the following frequency given:

[tex] f= 101.3 MHz[/tex]

We can convert this into Hz like this:

[tex] f= 101.3 MHz * \frac{10^6 Hz}{1 MHz}= 101300000 Hz[/tex]

If we have a fundamental wave we need to satisfy the following condition:

[tex] v = \lambda f[/tex]

If we solve for the wavelength we got:

[tex] \lambda = \frac{v}{f}[/tex]

We know that the velocity of the light is [tex] v= 3x10^8 m/s[/tex]

And if we replace into the last formula we got:

[tex]\lambda = \frac{3x10^8 m/s}{101300000 Hz}= 2.962 m[/tex]

Part b

For this case we can use the same formula but on this case the velocity of the sound at 20C is approximately 343 m/s, the frequency is given by:

[tex] f = \frac{v}{\lambda}[/tex]

We use the same wavelenght from the previous part [tex] \lamba = 2.962 m[/tex]

And if we replace the new values we got:

[tex] f= \frac{343 m/s}{2.962 m}= 115.8 Hz[/tex]

A. The wavelength is the wave is 2.96 m

B. The frequency of the wave is 115.87 Hz

The velocity, frequency and wavelength of a wave are related according to the following equation:

velocity (v) = wavelength (λ) x frequency (f)

v = λf

  • With the above formula, we can obtain the answers to the questions are follow:

A. Determination of the wavelength

Frequency (f) = 101.3 MHz = 101.3×10⁶ Hz.

Velocity (v) = 3×10⁸ m/s

Wavelength (λ) =?

[tex]\lambda = \frac{v}{f} \\ \\ \lambda = \frac{3 \times {10}^{8} }{101.3 \times {10}^{6}} \\ \\ \lambda = 2.96 \: m[/tex]

Therefore, the wavelength of wave is 2.96 m

B. Determination of the frequency of the wave

Velocity (v) of sound in air = 343 m/s

Wavelength (λ) = 2.96 m

Frequency (f) =?

[tex]f = \frac{v}{\lambda} \\ \\ f = \frac{343}{2.96} \\ \\ f = 115.87 \: Hz[/tex]

Therefore, the frequency of the sound wave is 115.87 Hz

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