Waves Details Flashcards
Do waves transfer energy?
Yes
Do waves transfer matter?
No
Wavefronts can be considered as…
-The peak of a transverse wave
-The compression of a longitudinal wave
The to-and-fro movements of waves are called…
oscillations
In transverse waves, the oscillations are…
at right angles to the direction of travel
Components of a longitudinal wave
-Compressions
-Rarefactions
In longitudinal waves, the oscillations are…
parallel to the direction of travel
Examples of transverse waves
-Electromagnetic waves
-Water waves
-Seismic S waves(secondary)
Examples of longitudinal waves
-Sound waves
-Seismic P waves(primary)
Waves can undergo…
-Reflection(at a plane surface)
-Refraction(due to a change in speed)
-Diffraction(through a narrow gap)
(In terms of diffraction)Wider gaps produce…
less diffraction
(In terms of diffraction)Longer wavelengths produce…
more diffraction
Features of sound waves
-Are caused by vibrations
-Are longitudinal waves
-Need a material(medium) to travel through
-Can travel through solids, liquids and gases
-Can be reflected, refracted and diffracted
Speed of sound waves in states of matter(in descending order)
-Solids(travel the fastest in)
-Liquids
-Gases(travel the slowest in)
SI unit of frequency
Hertz(Hz)
Features of the speed of sound
-Depends on the temperature of the air(increases in hot air)
-Does not depend on the pressure of the air
-Is different through different materials
Speed of sound
330m/s - 350m/s(approx.)
Approximate range of frequencies audible to humans
20Hz - 20,000Hz
(In terms of sound)The higher the frequency…
the higher the pitch of the sound
(In terms of sound)The longer the amplitude…
the louder the sound will be
Uses of ultrasound
-Echo-sounders(send ultrasound pulses downward into the sea to measure distance)
-Scanning wombs
-Cleaning delicate machinery
-Metal testing
Features of light
-Is a form of radiation
-Travels in straight lines
-Transfers energy
-Travels as waves
-Can travel through a vacuum
-The fastest thing in the universe
The laws of reflection
-The angle of incidence is equal to the angle of reflection
-The incident ray, reflected ray and normal all lie in the same plane
Rules for image size and position
-The image is the same size as the object
-The image is as far behind the mirror as the object is in front
(In terms of bending effect)the higher the refractive index of a medium…
the greater the bending effect(as it slows down light more)
Use of optical fibres
Signal carrier in telephone systems
Types of lenses
-Convex(convergeng) lens
-Concave(diverging) lens
Potential characteristics of an image
-Enlarged/Same size/Diminished
-Upright/Inverted
-Real/Virtual
How virtual images are formed
Diverging rays being extrapolated backwards
Traditional seven colours of the visible spectrum(in order of frequency and wavelength)
-Red(longest wavelength/lowest frequency)
-Orange
-Yellow
-Green
-Blue
-Indigo
-Violet(shortest wavelength/highest frequency)
Speed of light(in a vacuum)
300,000km/s
Speed of electromagnetic waves(in a vacuum)
300,000km/s
Light waves belong to a family of…
electromagnetic waves
Features of electromagnetic waves
-Can travel through a vacuum
-Are transverse waves
-Transfer energy
Electromagnetic waves all travel at the same speed in a vacuum(T/F)
True
Electromagnetic spectrum(in order of frequency and wavelength)
-radio waves(lowest frequency/longest wavelength)
-infrared rays
-light rays
-ultraviolet rays
-X-rays
-gamma rays(highest frequency/shortest wavelength)
radio waves(in order of frequency and wavelength)
-long wave(lowest frequency/longest wavelength)
-medium wave
-short wave
-VHF
-UHF
-microwaves(highest frequency/shortest wavelength)
Uses of long waves
long distance AM radio
Uses of medium waves
local AM radio
Uses of short waves
amateur radio
Uses of VHF
FM radio
Uses of UHF
TV broadcasts
Uses of microwaves
-Mobile phones
-Microwave ovens(heating effect)
-Satellite television
-Wi-Fi
Uses of infrared rays
-Electric grills
-Intruder alarms
-Thermal imaging
-Optical fibres
-TV remote controllers
Uses of light rays
-Vision
-Photography
-Illumination
Uses of ultraviolet rays
-Killing bacteria
-Sterilising water
-Security marking
-Detecting fake bank notes
Uses of X-rays
-X-ray photography(medical scanning)
-Security scanners
Uses of gamma rays
-Sterilising food and medical equipment
-Detecting and treating cancer
-Medical scanning
Harmful effects of excessive exposure to microwaves
Internal heating of body cells
Harmful effects of excessive exposure to infrared rays
Skin burns
Harmful effects of excessive exposure to ultraviolet rays
Damage to surface cells and eyes(leading to skin cancer and eye conditions)
Harmful effects of excessive exposure to X-rays and gamma rays
Mutation or damage to cells in the body
A sound can be transmitted as a…
-digital signal
-analogue signal
Features of analogue signals
-Varies continuously in both amplitude and frequency
-Signal can take one of many different values
Features of digital signals
-A series of pulses(of either 1s or 0s)
-Signal can only take 2 values(either a 1 or a 0)
Benefits of digital signalling
-Increased rate of transmission of data
-Increased range(due to accurate signal regeneration)
