Waves Flashcards
What do waves do
They travel in straight lines
Refract,reflect,diffract
Transfer energy from one place to another without the transfer of matter
…
How many pulses make up a full wave
2
What is a transverse wave
A transverse wave is a moving (progressive) wave that consists of oscillations occurring perpendicular (or right angled) to the direction of energy transfer.
What is a wavefront
Straight line across a wave where all particles are in phase
Wavelength
Distance between 2 corresponding points on 2 successive waves
Frequency
Number of waves complete per seconds
Time period
Time taken for one complete wave
Crest/peak
Highest part of a wave
Trough
Lowest part of a wave
Amplitude
Maximum displacement from the waves undisturbed position
Wave speed
Distance travelled by wavefront per second
Medium
Matter the wave is traveling through
Describe the disturbance of a transverse wave
The disturbance is 90 degrees to the direction of the wave
What is the difference between transverse and longitudinal waves
In a transverse wave, the disturbance is 90 degrees to the wave and they don’t require a medium to travel through
Longitudinal waves require medium and occur 180 degrees/in the same plane as the direction of the wave
Describe the displacement of the medium in longitudinal waves
Parallel to the propagation of the wave
What are the equivalents of peaks and troughs in longitudinal waves
Compressions and rarefactions
When do échos occur
when a wave is directly reflected from a boundary
Refraction
Bending of light when it passes from one medium to another of different optical densities and is caused by the changing of speed in the media
What happens to the wave speed, wave length, direction and frequency when a wave refracts
The wave speed, length and direction changes but frequency will remain the same
How can we minimize refraction
By limiting the angle at which the ray enters the new optical density
What is diffraction
The bending of waves through a gap
How does the size of the gap through which the wave diffracts affect the wavelength
The smaller the sound the larger the wavelength, the greater the wave will spread out through the gap
How does frequency affect the diffraction of a radio wave
High frequency is little diffraction
Low frequency is large diffraction
What are the advantages of digital signals
They carry
What is refractive index
The ratio of the speed of light in a vacuum to the speed of light in a medium
What is total internal reflection
Complete reflection of a light ray reaching a boundary with a less dense medium when the angle of incidence exceeds the critical angle
i>c
What are the uses for total internal reflection
Fibre optic cables-transmit light down fibres
Communication and medical examinations
What are the 3 parts in an optic fibre cable
Coating
Cladding
Core
What is the critical angle
The angle of incidence in the medium of greater optical density that results in an angle of refraction of 90 degrees
What are the 2 main types of lenses
Concave and convex
Diverging and converging
What happens when parallel light rays pass through a convex lense
They converge at one point called the principle focus.
What type of image will be produced when an object is closer to the lens that then focal point
A magnified virtual image
What type of image is formed when an object is further from the lens than the focal point
inverted and real
What does it mean if an image is real
The image can be projected on a screen
What is another word for backtracking lines
Extrapolating
Why does dispersion happen
The refractive index for frequencies of light is slightly different, causing the angle of refraction to vary by a small amount
What is dispersion
The refraction of white light as it passes and then disperses through a prism into 7 colours. The colour with the highest frequency and smallest wave length, violet refracts the most and red the least
Monochromatic
Light of a single frequency