4.4 Waves Flashcards
What is amplitude?
A wave’s maximum displacement from its equilibrium position.
What are Antinodes?
A position of maximum displacement in a stationary wave.
What is Coherence?
Waves with the same frequency and constant phase difference.
What is Constructive Interference?
The type of interference that occurs when two waves meet in phase. The wave amplitudes are superposed.
What is Critical Angle?
The angle of incidence that results in an angle of refraction of exactly 90°. It is when the refracted ray travels along the boundary line.
What is Destructive Interference?
The type of interference that occurs when the two waves are in antiphase. When one wave is at a peak and one is at a trough their addition results in a minimum point.
What is Diffraction?
The spreading of waves as they pass through a gap of a similar magnitude to their wavelength.
What is Displacement?
The distance that a point on a wave is from its equilibrium position.
What is the Electromagnetic Spectrum?
The spectrum of electromagnetic waves, consisting of Gamma Rays, X-Rays, Ultraviolet, Visible Light, Infrared, Microwaves and Radiowaves.
What are Electromagnetic Waves?
Waves that consist of perpendicular electric and magnetic oscillations. All electromagnetic waves travel at the speed of light in a vacuum.
What is Frequency?
The number of waves that pass a point in a unit time period. It is the inverse of the time period.
What is the Fundamental Mode of Vibration?
The oscillation of a wave at its natural frequency.
What is Intensity?
The power transferred per unit area. It is proportional to the square of a wave’s amplitude.
What is interference?
The superposition of the amplitudes of waves when they meet.
What are longitudinal waves?
A wave with oscillations that are parallel to the direction of energy propagation.
Sound waves are an example of a longitudinal wave. They cannot travel through a vacuum.
What are nodes?
A position of minimum displacement in a stationary wave.
What is an oscilloscope?
A device used to display and analyse waveforms.
What is path difference?
A measure of how far ahead a wave is compared to another wave, usually expressed in terms of the wavelength.
What is the period of a wave?
The time taken for a wave to complete one full cycle.
What is phase difference?
The difference in phase between two points on a wave. It is usually expressed in radians.
What is polarisation?
The restriction of a wave so that it can only oscillate in a single plane.
This can only occur for transverse waves.
What are progressive waves?
Waves that transfer energy from one point to another without a transfer of matter.
What is reflection?
The bouncing of a wave at a boundary. The angle of incidence will equal the angle of reflection.
What is refraction?
The changing of speed of a wave as it passes into a new medium.
If it passes into an optically denser medium, it will slow down.
What is refractive index?
A material property that is equal to the ratio between the speed of light in a vacuum, and the speed of light in a given material.
What is a stationary wave?
A wave that stores, but does not transfer, energy.
What is superposition in wave theory?
When two waves meet at the same point in space, their displacements combine and the total displacement becomes the sum of the individual displacements.
What is total internal reflection?
An effect that occurs in optical fibres, where full reflection occurs at the inside boundary of the fibre, meaning no radiation passes out. The angle of incidence must be greater than the critical angle for this to occur.
What are transverse waves?
A wave with oscillations that are perpendicular to the direction of energy propagation.
Electromagnetic waves are examples of transverse waves.
What is wave speed?
The product of a wave’s frequency and wavelength.
What is wavelength?
The distance between two identical positions on two adjacent waves, commonly measured from peak to peak or trough to trough.
What is the Young double-slit experiment?
An experiment that demonstrates the diffraction of light by passing monochromatic light across two narrow slits and observing the resulting pattern of bright and dark fringes.
What is the equation for wave speed?
Wave speed = frequency x wavelength
v = f y (lamda)
What is the equation for frequency?
Frequency = 1/ time period
f = 1/ T
What is the equation for intensity of the wave?
Intensity = power / area over which the wave spreads
I = P/A
What is the equation for wavelength? (With slits)
Wavelength = slit spacing x distance between fringes on screen / distance from slit to screen
What is the equation for Snells law?
Refractive index of the medium A x sin(A) = Refractive index of the medium B x sin(B)
What is the equation for angle of refraction when light passes from one medium to another?
Refractive index of first medium x sin(A) = refractive index of second medium x sin(B)
N(1) x sin(A) = N(2) x sin(B)
What is the equation to find the critical angle at which total internal reflection occurs?
Sin(critical angle) = 1 / refractive index of the denser medium
Sin(c) = 1/ n
What is the equation for refractive index?
Refractive index = speed of light / speed of light in medium
n = c / v
What is the wavelength (m) of radio waves?
10^3
What is the wavelength (m) of mircowaves?
10^-2
What is the wavelength (m) of infrared waves?
10^-5
What is the wavelength (m) of visible waves?
10^-6
What is the wavelength (m) of ultraviolet waves?
10^-8
What is the wavelength (m) of xrays?
10^-10
What is the wavelength (m) of gamma rays?
10^-12
What is the wavelength (m) of radio waves?
10^3
What is the wavelength (m) of mircowaves?
10^-2
What is the wavelength (m) of inrared waves?
10^-5
What is the wavelength (m) of visible wabes?
10^-6
What is the wavelength (m) of ultraviolet waves?
10^-8
What is the wavelength (m) of xrasy?
10^-10
What is the wavelength (m) of gamma rays?
10^-12
How are stationary waves formed?
Stationary waves are formed when two progressive waves with the same frequency and ideally the same amplitude, travelling in the opposite direction superpose.
