General Properties of Waves

Flashcards covering general properties of waves, wave parameters, the wave equation, transverse vs longitudinal waves, and wave behaviors (reflection, refraction, diffraction) in ripple tanks.

What do waves transfer as they travel from one location to another?

Waves transfer energy without transferring matter.

How do objects floating on water demonstrate that water waves transfer energy without transferring matter?

Floating objects bob up and down in fixed positions as waves pass beneath them, demonstrating that water particles oscillate vertically rather than moving along with the wave.

What is a wavefront as viewed from above?

A wavefront is drawn as a single line representing a single wave, where the distance between adjacent wavefronts represents the wavelength.

How is the amplitude ($A$) of a wave defined and measured?

Amplitude is the maximum displacement of a wave from its undisturbed position, measured in metres ($\text{m}$) from the undisturbed position to a crest or trough.

What is the definition and SI unit of wavelength ($\lambda$)?

Wavelength is the distance from one point on a wave to the exact same point on the next wave, measured in metres ($\text{m}$).

What is wave frequency ($f$) and what unit is used to measure it?

Frequency is the number of waves passing a point per second, measured in hertz ($\text{Hz}$).

What are wave crests (peaks) and troughs?

A crest (peak) is the highest point on a wave above its undisturbed position, and a trough is the lowest point below its undisturbed position.

In the provided diagram of a ripple tank wave cross-section, which letter represents the amplitude and which represents the wavelength?

Arrow D represents the amplitude (displacement from the undisturbed position to a peak), and arrow C represents the wavelength (distance between equivalent points on adjacent waves).

What is the wave equation relating wave speed ($v$), frequency ($f$), and wavelength ($\lambda$)?

$$v = f \times \lambda$$

What mathematical equations relate the frequency ($f$) and time period ($T$) of a wave?

$f = \frac{1}{T}$ and $T = \frac{1}{f}$

A wave in a pond has a speed of $0.15\,\text{m/s}$ and a time period of $2\,\text{s}$. What are its frequency and wavelength?

Frequency $f = \frac{1}{2} = 0.5\,\text{Hz}$; Wavelength $\lambda = \frac{0.15}{0.5} = 0.30\,\text{m}$.

What defines a transverse wave?

A wave in which the direction of vibration is perpendicular ($90^\circ$) to the direction of energy transfer.

What are three examples of transverse waves?

Electromagnetic waves (e.g., light, radio waves, X-rays), surface ripples on water, and seismic S-waves.

What defines a longitudinal wave?

A wave in which the direction of vibration is parallel to the direction of energy transfer / propagation.

What are compressions and rarefactions in longitudinal waves?

Compressions are regions where wave particles/coils are close together, and rarefactions are regions where they are spaced farther apart.

What are two main examples of longitudinal waves?

Sound waves and seismic P-waves.

Why can electromagnetic transverse waves travel through a vacuum, whereas longitudinal sound waves cannot?

Electromagnetic waves are non-mechanical and do not require particles to propagate, whereas longitudinal waves depend on particle vibrations and cannot travel through empty space.

How do density and pressure differ between transverse and longitudinal waves as they travel through a medium?

Transverse waves maintain constant density and pressure throughout the medium, whereas longitudinal waves cause local changes in density and pressure.

What is the normal line in wave behavior diagrams?

An imaginary line drawn perpendicular ($90^\circ$) to the boundary between two media.

What occurs when a wave undergoes reflection at a plane surface?

The wave hits a boundary between two media and bounces back within the original medium, keeping the angle of incidence equal to the angle of reflection.

What is refraction and what wave properties change during refraction?

Refraction is the change in wave speed as it passes across a boundary between two transparent media, causing changes in wavelength and direction while frequency remains constant.

What happens to the wavelength and direction of a wave when it slows down upon entering a denser medium or shallower water?

The wavefronts bunch together, the wavelength decreases, and the wave turns towards the normal line.

What is diffraction?

The spreading out of waves as they pass through a narrow gap or bend around an obstacle or edge.

Under what condition is diffraction through a gap most prominent?

When the width of the gap is approximately equal to the wavelength of the waves.

Based on the provided diagram, how does gap size affect the degree of diffraction when waves pass through a slit?

When the gap size is greater than the wavelength, minimal spreading occurs; when the gap size is approximately equal to or smaller than the wavelength, waves spread out significantly into circular wavefronts.

In a ripple tank refraction experiment using a glass block, how does water depth affect wave speed and wavelength?

The shallow water over the glass block causes the water waves to slow down and their wavelength to shorten compared to deep water.

How does altering the motor frequency in a ripple tank affect the wavelength of the generated water waves?

Higher motor frequencies produce waves with shorter wavelengths, whereas lower motor frequencies produce waves with longer wavelengths.