Question 1

Which of the following best describes a transverse wave?

Accepted Answer

The oscillations are perpendicular to the direction of wave propagation.

Question 2

A wave pulse travels along a string with a speed of $$v = 134\ \mathrm{cm/s}$$ and a frequency of $$f = 5\ \mathrm{Hz}. $$What is the wavelength of the wave?

Accepted Answer

$$\lambda = 26.8\ \mathrm{cm}$$

Question 3

Which equation correctly relates the speed $$v$$, frequency $$f$$, and wavelength $$\lambda of a $$wave?

Accepted Answer

$$v = f \lambda$$

Question 4

A sound wave propagates through air with a speed of $$v = 343\ \mathrm{m/s}. If $$the frequency of the sound is $$f = 686\ \mathrm{Hz}$$, what is its wavelength?

Accepted Answer

$$\lambda = 0.5\ \mathrm{m}$$

Question 5

Which of the following statements about the principle of superposition is correct?

Accepted Answer

When two waves overlap, their amplitudes add algebraically at each point.

Question 6

A string is under tension and a wave pulse is sent down the string. If the tension in the string is increased, what happens to the speed of the wave?

Accepted Answer

The speed increases.

Question 7

The intensity $$I of a $$spherical wave at a distance $$r$$ from the source is given by:

Accepted Answer

$$I = \dfrac{P}{4\pi r^2$}$$

Question 8

A person hears a sound at the threshold of hearing, which corresponds to an intensity of $$I_0 = 1.0$$ 	imes $$10^{-12}$$\ \mathrm{$$W/m^2$$}$$. What is the sound intensity level in decibels (dB)?

Accepted Answer

$$0\ \mathrm{dB}$$

Question 9

Two speakers are placed 285 m apart and emit sound waves in phase. A person stands 100 m from the midpoint between the speakers and hears a minimum in sound intensity. If the speed of sound is $$v = 343\ \mathrm{m/s}$$, what is the frequency of the sound waves?

Accepted Answer

$$f = 343\ \mathrm{Hz}$$

Question 10

Which of the following best describes constructive interference?

Accepted Answer

Two waves overlap and their amplitudes add to produce a larger amplitude.

Question 11

A wave on a string is reflected at a boundary where the string is attached to a denser medium. What happens to the reflected wave?

Accepted Answer

It is inverted.

Question 12

The Doppler effect causes a change in observed frequency when:

Accepted Answer

Either the source or the observer is moving relative to the medium.

Question 13

A stationary observer hears a frequency of $$f' = 1380\ \mathrm{Hz}$$ from a truck approaching at speed $$v. If $$the actual frequency emitted by the truck is $$f = 1300\ \mathrm{Hz}$$ and the speed of sound is $$v_s = 343\ \mathrm{m/s}$$, what is the speed of the truck?

Accepted Answer

$$v = 19.8\ \mathrm{m/s}$$

Question 14

Which of the following is the correct mathematical form for a sinusoidal wave traveling in the positive $$x-$$direction?

Accepted Answer

$$y(x, t) = A \cos(kx - \omega t + \phi)$$

Question 15

The speed $$v of a $$wave on a string under tension $$T$$ and with mass per unit length $$\mu is $$given by:

Accepted Answer

$$v = \sqrt{\dfrac{T}{\mu}}$$

Question 16

Standing waves are formed when:

Accepted Answer

Two waves of the same frequency and amplitude travel in opposite directions and interfere.

Question 17

The beat frequency heard when two sound waves of frequencies $$f_1$$ and $$f_2$$ interfere is:

Accepted Answer

$$|f_1$ - f_2$|$$

Question 18

Which property of a wave determines the pitch of a sound?

Accepted Answer

Frequency

Question 19

A wave pulse described by $$y(x, t) = A \exp\left(-\dfrac{(x - vt)^2$}{2\$$sigma^2$$}\right)$$ moves to the right. What is the maximum displacement of the pulse?

Accepted Answer

$$A$$

Waves: Types, Properties, and Mathematical Descriptions

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