Question 1

Which of the following best describes a longitudinal wave?

Accepted Answer

A wave in which particle displacement is parallel to the direction of wave propagation.

Question 2

A sound wave travels through air with a speed $$v = 343 \ \mathrm{m/s}$$ and a frequency $$f = 440 \ \mathrm{Hz}. $$What is its wavelength?

Accepted Answer

$$\lambda = \dfrac{v}{f} = \dfrac{343}{440} \approx 0.78 \ \mathrm{m}$$

Question 3

Which statement about the superposition principle is correct?

Accepted Answer

The superposition principle states that the resultant displacement at any point is the sum of the displacements due to each wave at that point.

Question 4

A standing wave is formed on a string fixed at both ends. If the length of the string is $$L$$ and the wavelength of the fundamental mode is $$\lambda$$, what is the relationship between $$L$$ and $$\lambda$$?

Accepted Answer

$$L = \dfrac{\lambda}{2}$$

Question 5

Which of the following best explains the Doppler Effect for sound waves?

Accepted Answer

The frequency of a sound increases as the source approaches the observer and decreases as it moves away.

Question 6

A wave traveling in a medium encounters a boundary with a second medium of lower impedance. What happens to the reflected wave?

Accepted Answer

It is reflected with no phase change.

Question 7

Which equation correctly expresses the relationship between pressure amplitude $$P$$ and displacement amplitude $$s$$ for a sound wave in a medium with density $$\rho$$ and speed of sound $$v$$?

Accepted Answer

$$P = \rho v^2$ s$$

Question 8

A harmonic wave is described by $$y(x, t) = A \sin(kx - \omega t). $$What does $$\omega$$ represent?

Accepted Answer

The angular frequency of the wave.

Question 9

Which of the following is true about electric charge according to the study materials?

Accepted Answer

Electric charge is quantized and is always an integer multiple of the elementary charge.

Question 10

Coulomb's law gives the force between two point charges $$q_1$$ and $$q_2$$ separated by distance $$r. $$Which is the correct formula?

Accepted Answer

$$F = k \dfrac{q_1$ q_2$}{r^2$}$$

Question 11

A dipole consists of charges $$+q$$ and $$-q$$ separated by distance $$d. $$What is the magnitude of its dipole moment?

Accepted Answer

$$p = qd$$

Question 12

Which of the following best describes the polarization of an electric dipole in an external electric field?

Accepted Answer

The dipole aligns parallel to the electric field.

Question 13

A sound wave passes from air into water. Which of the following statements is correct regarding its speed and wavelength?

Accepted Answer

The speed increases and the wavelength increases.

Question 14

Which formula gives the intensity $$I of a $$sound wave as a function of distance $$r$$ from a point source emitting power $$P$$?

Accepted Answer

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

Question 15

Which of the following is a correct statement about nodes and antinodes in a standing wave?

Accepted Answer

Nodes are points of zero displacement and antinodes are points of maximum displacement.

Question 16

A medical ultrasound device emits a pulse at $$2 \ \mathrm{MHz}$$ into human tissue. If the speed of sound in tissue is $$1540 \ \mathrm{m/s}$$, what is the wavelength of the ultrasound?

Accepted Answer

$$\lambda = \dfrac{1540}{2 	imes 10^6$} = 0.00077 \ \mathrm{m}$$

Question 17

Which of the following best describes the Beer-Lambert law in acoustics?

Accepted Answer

It relates the absorption of sound to the thickness of the medium and the intensity of the incident wave.

Question 18

Two point charges $$+q$$ and $$-q$$ are placed a distance $$d$$ apart. What is the direction of the electric field at a point exactly midway between them?

Accepted Answer

The electric field points from $$+q to$$ $$-q.$$

Question 19

A wave pulse on a string reflects from a fixed end. What happens to the phase of the reflected pulse?

Accepted Answer

The reflected pulse is inverted (phase change of $$180^\circ).$$

Key Concepts in Waves, Acoustics, and Electrostatics

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