Q: A radio station broadcasts at a frequency of $$1230 \times 10^3$ Hz. If the speed of electromagnetic waves is 3.00$$ \times $$10^8 m/s$$, what is the wavelength of the radio wave?

$$\lambda = 2.44 \times 10^2$ m

Q: The intensity $$I of a $$sound wave is defined as $$I = \frac{P}{A}. If $$the power passing through a surface is $$1.2 \times 10$$^{-5}$$ W and the area is 4.0$ m^2$, what is the intensity?

$$3.0 \times 10$$^{-6}$$ W/m^2$

Question 1

Which of the following best describes the difference between a transverse wave and a longitudinal wave?

Accepted Answer

In a transverse wave, the particles of the medium move perpendicular to the direction of wave propagation, while in a longitudinal wave, they move parallel.

Question 2

A radio station broadcasts at a frequency of $$1230 	imes 10^3$ Hz. If the speed of electromagnetic waves is 3.00$$ 	imes $$10^8 m/s$$, what is the wavelength of the radio wave?

Accepted Answer

$$\lambda = 2.44 	imes 10^2$ m

Question 3

The speed of a wave on a string is given by $$v = \sqrt{\frac{F}{\mu}}. If $$the tension $$F in $$the string is quadrupled, what happens to the speed of the wave?

Accepted Answer

The speed doubles.

Question 4

A sound wave in air has a frequency of 1000 Hz and a wavelength of 0.343 m. What is the speed of sound in air under these conditions?

Accepted Answer

$$v = 343 m/s$$

Question 5

Which of the following statements about sound waves is correct?

Accepted Answer

Sound waves are longitudinal waves that require a medium to propagate.

Question 6

A guitar string of length 0.628 m and mass 0.208 g is under a tension of 226 N. What is the speed of the wave on the string? (Use $$v = \sqrt{\frac{F}{\mu}}$$ and $$\mu = \frac{m}{L})$$

Accepted Answer

$$v = 826 m/s$$

Question 7

The period $$T of a $$wave is 0.01 s. What is its frequency $$f$$?

Accepted Answer

$$f = 100 Hz$$

Question 8

Which property of a sound wave primarily determines its loudness as perceived by the human ear?

Accepted Answer

Pressure amplitude

Question 9

The intensity $$I of a $$sound wave is defined as $$I = \frac{P}{A}. If $$the power passing through a surface is $$1.2 	imes 10$$^{-5}$$ W and the area is 4.0$ m^2$, what is the intensity?

Accepted Answer

$$3.0 	imes 10$$^{-6}$$ W/m^2$

Question 10

A sound source emits power $$P$$ uniformly in all directions. At a distance $$r$$ from the source, the intensity is given by $$I = \frac{P}{4\pi r^2$}. If $$you move twice as far from the source, what happens to the intensity?

Accepted Answer

It decreases by a factor of 4.

Question 11

The decibel level $$\beta is $$defined as $$\beta = 10 \log_{10}\left(\frac{I}{I_0$}ight)$$, where $$I_0 = 1.0$$ 	imes $$10^{-12} W/m$^2. $$What is the intensity level in dB for a sound with intensity $$I = 1.0 	imes 10$$^{-6}$$ W/m^2$?

Accepted Answer

$$60 dB$$

Question 12

A train is moving towards a stationary observer at a speed of 44.7 m/s. The horn emits a frequency of 415 Hz. If the speed of sound is 343 m/s, what frequency does the observer hear as the train approaches?

Accepted Answer

$$477 Hz$$

Question 13

Which of the following best explains why you see lightning before you hear thunder during a thunderstorm?

Accepted Answer

Light travels much faster than sound.

Question 14

Ultrasound imaging in medicine relies on which physical principle?

Accepted Answer

Reflection of high-frequency sound waves from tissue boundaries

Question 15

A sound wave in water travels faster than in air primarily because:

Accepted Answer

Water molecules are closer together, allowing faster transmission of vibrations.

Question 16

If the frequency of a sound wave doubles but its speed remains constant, what happens to its wavelength?

Accepted Answer

The wavelength is halved.

Question 17

A Doppler ultrasound is used to measure blood flow. If red blood cells move towards the probe, what happens to the frequency of the reflected sound?

Accepted Answer

The frequency increases.

Question 18

Which of the following is true about the motion of particles in a water wave?

Accepted Answer

Particles move in circular paths, combining both transverse and longitudinal motion.

Question 19

If a sound intensity increases from $$1.0 	imes 10$$^{-6}$$ W/m^2$ to 1.0$$ 	imes $$10^{-4} W/m$^2$$, by how many decibels does the intensity level increase?

Accepted Answer

20 dB

Question 20

A person hears a sound at 80 dB and another at 60 dB. How many times more intense is the first sound compared to the second?

Accepted Answer

100 times more intense

Waves and Sound: Principles, Properties, and Applications

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