Module 4.4 Flashcards
Amplitude
A wave’s maximum displacement from its equilibrium position.
Antinodes
A position of maximum displacement in a stationary wave
Coherence
Waves with the same frequency and constant phase difference
Constructive Interference
The type of interference that occurs when two waves
meet in phase. The wave amplitudes are superposed.
Critical Angle
The angle of incidence that results in an angle of refraction of
exactly 90 degrees. It is when the refracted ray travels along the boundary line
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
Diffraction
The spreading of waves as they pass through a gap of a similar
magnitude to their wavelength
Displacement
The distance that a point on a wave is from its equilibrium
position.
Electromagnetic Spectrum
The spectrum of electromagnetic waves, consisting
of Gamma Rays, X-Rays, Ultraviolet, Visible Light, Infrared, Microwaves and
Radiowaves
Electromagnetic Waves
Waves that consist of perpendicular electric and
magnetic oscillations. All electromagnetic waves travel at the speed of light in a
vacuum.
Frequency
The number of waves that pass a point in a unit time period. It is the
inverse of the time period
Fundamental Mode of Vibration
The oscillation of a wave at its natural
frequency
Intensity
The power transferred per unit area. It is proportional to the square of a
wave’s amplitude.
Interference
The superposition of the amplitudes of waves when they meet
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
Nodes
A position of minimum displacement in a stationary wave
Oscilloscope
A device used to display and analyze waveforms
Path Difference
A measure of how far ahead a wave is compared to another
wave, usually expressed in terms of the wavelength.
Period
The time taken for a wave to complete one full cycle
Phase Difference
The difference in phase between two points on a wave. It is
usually expressed in radians.
Polarization
The restriction of a wave so that it can only oscillate in a single
plane. This can only occur for transverse waves.
Progressive Waves
Waves that transfer energy from one point to another
without a transfer of matter.
Reflection
The bouncing of a wave at a boundary. The angle of incidence will
equal to the angle of reflection
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
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.
Stationary Wave
A wave that stores, but does not transfer, energy.
Superposition
When two waves meet at the same point in space their
displacements combine and the total displacement at that point becomes the sum
of the individual displacements at that point
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
Transverse Waves
A wave with oscillations that are perpendicular to the
direction of energy propagation. Electromagnetic waves are examples of
transverse waves
Wave Speed
The product of a wave’s frequency and wavelength
Wavelength
The distance between two identical positions on two adjacent
waves. It is commonly measured from peak to peak or trough to trough.
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 oscillations is an in phase phase difference
(n X 2π)λ
What oscillations is an antiphase phase difference
(2n + 0.5)λ
How to determine frequency
To determine the frequency of a wave, an oscillation is fed a signal. The time base on the oscilloscope can be set on the x-axis to represent time and y-axis to represent amplitude. The time taken to complete one full oscillation can be measured then used to find the frequency
Wavelength and frequency of radio waves
10^3 and 3 X10^9
Wavelength and frequency of micro waves
10^-2 and (3 x 10^9 - 3 x 10^11)
Wavelength and frequency of Infra-red
10^-5 and (3 x 10^11 - 4.3 x 10^14)
Wavelength and frequency of Visible radiation
0.5 x 10^-6 and (7.5 x 10^14 - 4.3 x 10^14)
Wavelength and frequency of ultra-violet
10^-8 and (7.5 x 10^14 - 3 x 10^16)
Wavelength and frequency of X-rays
10^-10 and (3 x 10^16 - 7.5 x 10^20)
Wavelength and frequency of Gamma rays
10^-12 and (3 x 10^18 - 3 x 10^24)
2 conditions for total internal reflection
- the light must be travelling from a material with a higher refractive index to a lower refractive index.
- the angle of incidence ray must be above the critical angle
1st harmonic
- String never crosses
- frequency = 20Hz
- 1 multiple of the fundamental frequency
- λ = 2L where L is the length of the string
2nd harmonic
- String crosses once
- frequency = 40Hz
- 2 multiples of the fundamental frequency
- λ = L
3rd harmonic
- String crosses 2 times
- frequency = 60Hz
- 3 times the fundamental frequency
- λ = 2/3 L
4th harmonic
- string crosses 3 times
- frequency = 80Hz
- 4 times the fundamental frequency
- λ = 1/2 L
5th harmonic
- string crosses 4 times
- frequency = 100 Hz
- 5 times the fundamental frequency
- λ = 2/5 L
What is the phase difference of a wave and what is it measured in
The amount one wave lags behind another as a proportion of the wavelength. Measured in rad
What do each of the axes on an oscilloscope measure
Vertical - Voltage / amplitude of the wave
Horizontal - time
Wavelength and frequency of red light
620-750 nm
400-484 THz
Wavelength and frequency of orange light
590-620 nm
484-508 THz
Wavelength and frequency of yellow light
570-590 nm
508-526 THz
Wavelength and frequency of green light
495-570 nm
526-606 THz
Wavelength and frequency of blue light
450-495 nm
606-668 THz
Wavelength and frequency of violet light
380-450 nm
668-789 THz
