Waves p12 and 11 Flashcards
Transverse waves
The direction of oscillation is perpendicular (at right angles)to the direction of wave motion
Longitudinal waves
The direction of oscillation is parallel to the direction of wave motion
Electromagnetic waves share these properties
electromagnetic waves travel at the speed of light v=3x10^8m/s
Can travel through a vacuum
All transverse waves
High frequency waves have high energy whereas low frequency waves have low energy
Sources of radio waves
Alternating current in an electrical circuit creates an electromagnetic wave, a radio wave
Radio waves effects on body
Radio waves pass through the body without being absorbed
Radio waves what can this type of wave be used for
Broadcasting communications;carrying signals for radio and TV Navigation and radar Studying universe: astronomy Control signals e.g. garage doors Tracking and automatic identification
Sources of microwaves
Satellites
Microwave ovens
The sun
Effects on body microwaves
Some wavelengths of microwaves can be absorbed causing heating of cells which may be dangerous
Microwaves what can this type of wave be used for
Communications:mobile phones and satellite transmissions
Cooking:heating food in microwave ovens
Sources of infrared radiation
Is given off by all objects the hotter the object the more infrared radiation
Infrared radiation effects on the body
Mostly reflected or absorbed by the skin, causing some heating too ,it can cause burns if the skin gets too hot
Infrared radiation what can this type of wave be used for
Thermal imaging/night vision cameras Television remote controls Short range communications Optical fibres Security systems Cooking and heating
Sources of visible light
Lightbulbs and the sun
Visible light effect on the body
Mostly absorbed or reflected by the skin but can cause some heating effects
Visible light what can this type of wave be used for
Vision Photography Illumination Photosynthesis Fibre optic communication
Sources of ultraviolet
Produced by the sun and uv lamps
Ultraviolet effects on the body
Damage cells which may cause genetic mutations and cancer and can lead to tissue damage or radiation sickness
Ultraviolet what can this type of wave be used for
Sun tan beds Security markers Fluorescent lamps Detecting forged bank notes Disinfecting water
X-rays sources
X-ray tubes produce x-rays when electrons or other particles travelling at high speed are stopped
X rays effect on the body
Can cause cell damage by radiation if exposed
X rays what can this type of wave be used for
Medical x-rays
Observing the internal structure of objects
Airport security scanners
Gamma rays sources
Produced by radioactive substances when unstable nuclei release energy
Gamma rays effects on the body
Damages healthy cells in our body but can kill cancer cells
Gamma rays what can this type of wave be used for
Sterilising food and medical equipment
Detection of cancer and its treatment
Radioactive tracers to detect where substances go;human bodies, leaky pipes, machinery
Electromagnetic spectrum from longest wavelength to shortest wavelength
Radio waves->microwaves->infrared radiation->visible light->ultraviolet->x-rays->gamma rays
What is an oscillation
The period of an oscillation is the time it takes for one full oscillation to happen.
What is a wave
A wave is a series of oscillations that travel from one place to another, transferring energy.
The human eye can only detect
Visible light, the wavelength of visible light ranges from just below 400nm to above 700nm
Electromagnetic waves transfer
Energy from a source to an absorber
V(wave speed m/s)=
F(frequency Hz) x wavelength(m)
