Medical Physics Midterm Review - Waves, Sound, Music, and Electromagnetic Waves

Vocabulary flashcards covering key topics in Medical Physics Midterms, including wave properties, wave behaviors, sound characteristics, human audition, acoustics, music, and electromagnetic fields.

Waves

Rhythmic disturbances that carry energy without carrying matter.

Crest

The peak or highest point of a wave.

Trough

The lowest point of a wave.

Rest Position

The undisturbed position of particles in a medium when they do not vibrate.

Amplitude

The maximum disturbance from a wave's crest to its rest position, equal to one-half the distance between a crest and a trough.

Wavelength

The set distance representing a full cycle of a wave, measured from crest to crest, trough to trough, or compression to compression.

Frequency

The number of waves passing a specific point per second, expressed in Hertz ($Hz$).

Mechanical Waves

Waves that require a medium (solid, liquid, or gas) to transfer energy.

Longitudinal Waves

Mechanical waves (also known as compressional waves) in which matter in the medium moves forward and backward along the same direction that the wave travels.

Transverse Waves

Waves in which particle vibration occurs at right angles to the direction of the wave's travel.

Sound Waves

Mechanical longitudinal waves produced when air surrounding a vibrating object vibrates, traveling through a series of compressions and rarefactions.

Electromagnetic Waves

Transverse waves composed of oscillating electric and magnetic fields vibrating at right angles to the direction of travel, which do not require a medium.

Reflection

The wave behavior where a wave strikes an object and bounces off, such as light rays producing images in a mirror or sound producing an echo.

Refraction

The bending of a wave as it moves from one medium to another, caused by a change in the wave's speed.

Diffraction

The bending or spreading of waves around a barrier or through a small opening.

Interference

The ability of two waves to combine and form a new wave, which can be destructive to reduce noise.

Primary Waves ($P$-waves)

Seismic waves that require a physical medium to travel.

Secondary Waves ($S$-waves)

Seismic waves that do not require a physical medium to travel.

Wave Velocity Formula

The equation $v = f \times \frac{}{}$ where $v$ is velocity, $f$ is frequency, and $\frac{}{}$ represents wavelength.

Ultrasonography

A medical application using focused sound waves diagnostically and therapeutically, such as cleaning teeth, breaking up cataracts, and fragmenting gallstones or kidney stones.

Sonar

A system using sound waves to track underground objects, read underwater current compositions, and map the ocean floor.

Young's Modulus ($E$)

The measure of a material's stiffness or resistance to deformation, calculated as $E = \frac{\text{stress}}{\text{strain}}$.

Bulk Modulus ($K$)

The measure of a substance's resistance to compression, defined as $K = -\frac{\frac{\text{Delta} P}{\text{Delta} V}}{V}$.

Pitch

How high or low a sound is, determined directly by the frequency of vibrations.

Loudness

The human perception of how much energy a sound wave carries, determined by the wave's amplitude.

Timbre (Quality)

The acoustic characteristics that distinguish sounds from different sources even when they share the same pitch and loudness.

Duration

The length of time that a sound lasts.

Decibel Scale ($dB$)

A scale describing the energy carried by sound waves, where an increase of $10,dB$ represents a 10-fold energy increase and hearing damage begins at $85,dB$.

Vocal Cord Mechanics

Sound creation via exhaling past vocal cords; shorter, thinner cords vibrate at higher frequencies, while longer, thicker cords vibrate at lower frequencies.

Sound Transmission

The passing of sound energy through a material or from one medium to another.

Sound Absorption

The process by which soft or porous materials take in sound energy and convert it into a small amount of heat instead of reflecting it.

Echolocation

The orientation and navigation mechanism used by animals and visually impaired humans to estimate room sizes and shapes by interpreting reflected sound waves.

Doppler Effect

The apparent change in sound frequency that occurs when a sound source moves relative to a listener.

Music

Sounds deliberately produced to create a regular, organized pattern of pitches or notes.

Noise

A group of disorganized and irregular sounds with no regular pattern.

Natural Frequency

The specific frequency at which an object naturally vibrates.

Resonance

The phenomenon occurring when an object absorbs energy from a sound wave or vibrating object at its natural frequency and begins to vibrate.

Fundamental Frequency

The lowest frequency produced by a vibrating object.

Overtones

Higher frequencies that ring out simultaneously above the fundamental frequency of a vibrating object.

Beats

The periodic variation in sound volume heard each second, equal to the numerical difference between the frequencies of two simultaneous notes.

Reverberation

Repeated echoes produced by sound reflecting off hard surfaces.

Resonator

A hollow chamber containing air that absorbs energy from a vibrating string and vibrates at its natural frequencies to amplify sound.

Force Field

A region enabling an object to exert forces on other objects without physical contact, such as Earth's gravitational field or an electromagnetic field.