Waves/Pulses Flashcards
Wave?
A single disturbance traveling through a medium. A wave transfers energy though a medium without moving the medium permanently.
Transverse Wave?
A continual series of waves in which the vibration of particles in the medium is perpendicular to the direction of motion.
Crest?
The maximum position on a transverse wave.
Trough?
The minimum position on a transverse wave.
Amplitude?
The magnitude of the maximum displacement from the equilibrium or rest position. Usually taken from rest position to either crest or trough.
Oscillation?
When a particle is back in the same position as where it started and has the same motion as when it started.
Period?
The time required to complete one full oscillation.
Frequency and what is it’s S.I. unit?
The number of waves passing a point every second. Hertz (Hz).
How do you identify if any points are in phase?
When they have identical motion and are travelling at the same speed in the same direction. Two adjacent points in phase are also one wavelength apart and most easily measured from one crest/trough to the next crest/trough.
List the properties affecting and not affecting wave speed?
Wave speed is affected by properties of the medium ex: density and tension. Wave speed is however, not effected by properties of the wave, ex: period, frequency, wavelength and amplitude.
Longitudinal Waves?
Are the continuous propagation of disturbances through a medium, in which the particles of the medium oscillate in a direction parallel to the direction of the motion of the wave.
Compression?
A place where the particles in the medium are packed closely together. In sound waves, compressions are regions of high pressure.
Rarefaction?
A place where the particles in the medium are stretched far apart. In sound waves, rarefactions are regions of low pressure.
How are sound waves made?
They are created by vibrations in a given medium in the direction of the propagation. These vibrations cause regular variation in pressure in the given medium.
Equilibrium (rest) position?
The position of a particle when no wave is passing through it.
Wavelength?
The shortest distance between two successive points in phase. For longitudinal waves, they are measured as the shortest distance between two successive compressions or rarefactions.
Pitch and what does it depend on?
It describes how high or low a sound is and it depends on the frequency of the wave. Therefore, direct proportionality.
What is the normal range of human hearing?
From 20 Hz to 20 000 Hz (20kHz).
Audible Sound?
Sound within the human hearing range.
Infrasound?
Sound below the human hearing range.
Ultrasound?
Sound above the human hearing range.
Loudness and how is it graphically identified?
The measurement of the amount of energy transported by the sound. A large amplitude on a graph indicates more energy and thus, the sound is loud.
Decibel and what is its S.I. unit?
The decibel is used to compare the loudness of different sounds. S.I. unit: dB.
What are the human hearing thresholds?
Threshold of hearing: 0 dB, arbitrarily set to correspond to the softest sound humans can hear.
Threshold of pain: Sounds above 130 dB can cause pain and eventually damage to the ears.
Noise pollution?
Unpleasant or disturbing sounds in the environment that affects the health and well-being of humans and other living organisms.
What is the frequency of ultrasound?
From 20 kHz to 100 kHz.
Electromagnetic Waves?
Waves that travel at the speed of light (in a vacuum).
List the seven types of electromagnetic waves in order of smallest wavelength.
Gamma Rays, X-rays, Ultraviolet, Visible Light, Infrared, Micro Waves and Radio Waves.
Photons?
They can be thought of as parcels of electromagnetic radiation. Each photon carries its own amount of energy.
