##### Physics 67
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#### Complete List of Terms and Definitions for Physics 67

Terms Definitions
Frequency ds
Vibration A repeated disturbance
Echo A reflected sound wave.
Draw and Label compression, rarefaction, and wavelength of a longitudinal wave.
Wavelength Distance between *consecutive* points on a wave
Harmonics WHOLE NUMBER MULTIPLES OF THE FUNDAMENTAL FREQUENCY OF A STANDING WAVE.
Draw and Label Crest, Trough, Wavelength, and Amplitude of a Transverse wave.
Plane Mirror Mirror with a flat surface.
Convex Mirror Mirror that is curved outward.
Concave Mirror Mirror that is curved inward.
Lens A curved transparents object that forms an image by refracting light: also part of the eye that refracts light to focus an image on the retina.
Waves
Amplitute, A
Wavelength, λ
Frequency, f
Period, T
Wave Velocity
Crest/Trough
vwave = λf

λ = v/f
Diffraction SPREADING OF WAVES INTO THE GEOMETRIC SHADOW WHEN PASSING THROUGH A SLIT (OR OBSTACLE) WHOS SIZE IS COMPARABLE TO THE WAVELENGTH.
Polarised ALL PARTICLES ARE OSCILLATING IN THE SAME PLANE(OR FOR EM THE FIELDS DON'T ALTER THEIR PLANE OF OSCILLATION)
Longitudinal Waves PARTICLES VIBRATE PARALLEL TO THE DIRECTION OF PROPAGATION
Longitudinal -pieces of medium vibrate parallel to direction of travel
What are nodes? Points of destructive interference that result in minimum (zero) amplitude.

Amplitude

As waves travel, they set up patterns of disturbance.
The amplitude of a wave is its maximum disturbance from its undisturbed position.
It is the distance between the top and the middle of a wave.
Opaque Matter that does not transmit any light.
Echolocation The process of using reflected sound waves to find objects.
Amplitude Maximum displacement of a particle on the wave.
trough any long depression or hollow, as between two ridges or waves.
What is amplitude? Amplitude (A) is the maximum displacement from the mean position. (To the top of a crest or bottom of a trough from the middle line in either graph).
Coherence WAVES ARE COHERENT IF THEY HAVE A CONSTANT PHASE RELATTIONSHIP
Destructive interference AN ODD NUMBER OF HALF WAVELENGTHS RESULTS IN ANNULMENT (MINIMAS)
What is the wave equation for the velocity of a wave using frequency.

Moving Observer
- frequency increase if the moving towards, decreases if moving away.
Wavelength does not change. The actual speed of the wave does not change but to the observer the speed appears to change. F1=f(v±vs /v), moving away source (-), moving towards source (+)

Frequency

The frequency of a wave is the number of waves produced by a source each second.
It is also the number of waves that pass a certain point each second.
Resonant Frequencies The frequency at which standing waves are produced.
Medium A solid, liquid or gas that is vibrated.
Progressive Waves Transfer energy from one point to another
Phase Position of a particle in terms of Degrees or Radians, like a clock face from the axis.
Displacement Distance of a Particle on the wave from its equilibrium position.
radiation the process in which energy is emitted as particles or waves.
Incident Wave The name givien to an incoming wave
Rarefaction Part of a longitudinal wave in which the particles are spread apart
What is the wave equation? wavespeed = frequency x wavelength
Law of Reflection angle of incidence equals angle of reflection
Superposition WHEN TWO OR MORE WAVES OVERLAP AT A POINT, THE RESULTANT DISPLACEMENT IS THE VECTOR SUM OF THE DISPLACEMENTS OF THE ORIGINAL WAVES.
What causes constructive interference? When the resultant displacement is greater than either pulse.
What causes destructive interference? When the resultant displacement is less than that of either pulse.
How do you find the time period? T = 1/frequency
Malus’ Law - used to calculate the intensity of light after being polarized. I=Iθcos2 θ where I= intensity of polarized light, Iθ=is the original intensity of light, θ= is the angle between the polarizer.
Standing Wave A wave that forms a stationary pattern (harmonic) in which portions of the wave are at a rest position due to destructive interference and other parts of the wave have a large amplitude.
Transverse Wave Waves in which the particles of the medium vibrate with an up and down motion.
Virtual Image An image through which light does not actually pass.
refraction the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different.
Constructive Interference When waves interact anad the new wave is bigger then all the waves that produced it
Combination Wave A wave that has properties of both longitudinal and transverse wave
Longitudinal Wave A wave in which the vibrations are parallel to the propagation
Mechanical Wave Waves that need a physical medium to propagate
Simple Harmonic Motion (2) Restoring force is proportional to the negative of the displacement
SHM waves are sinusoidal
Is the wave speed greatest in the least dense or most dense medium? The least dense.
Brewster’s Law - Find the angle at which light is 100% polarized. Tan θ = n1/n2
Where  θ= the incident angle, n2 = index of refraction of reflective material, n1 = index of refraction of the medium the wave is incident to
Incidence The falling of a beam of light on a surface.
Reflection The bending of a wave as it passes at an angle from one medium to another. The speed of a wave depends on the medium. When the speed changes the wave changes its angle.
What is the unit of frequency? Frequency is measured in hertz (Hz)
When is the speed of the reflected pulse the same as the speed of the incident pulse? During fixed end reflection.
What is the pulse that returns in the initial medium after bouncing off the other medium? The reflected pulse.
What is waveleaght (upside down y) distance between two successive points that are in phase. measured in meters
Definition of a Wave The movement of energy from one point to another
Partial Reflection When some of the energy of the wave is transmitted into a new medium and some of the wave is reflected back
What is Amplitude (a) Height of a wave noting the energy it carries, measured in meters
What are the movements in a longitudinal wave?

The movements are backwards and forwards in longitudinal waves.
From a LESS dense medium to MORE dense, how does the speed of the transmitted pulse compare to the reflected pulse?From a less dense medium to more dense, how does the wavelength of the transmitted pulse compare to the INCIDENT pulse? Speed is slower, wavelength is shorter.
Define a Transverse Wave. Give an example The particles in the medium oscillate about their positions perpendicular to the direction of motion of the wave.
What's special about electomagnetic waves, give an example. Need no medium, travel at C in a vacuum. e.g Light, Radio, Microwaves...
From a MORE dense medium to a LESS dense, which pulse (transmitted or reflected) are on the opposite side (out of phase) as the incident phase? the transmitted pulse and the reflected pulse
What is the equation for the speed of sound?

speed of sound = distance travelled
time taken
What's special about mechanical waves, give the main example. They need a medium to travel in, e.g Sound, Slinky Spring
Is the amplitude of the incident pulse greater or smaller than the amplitude of the reflected pulse? The amplitude of the incident pulse is always greater than the amplitude of the reflected pulse.