ElectroMagnegnetic Waves COPY Flashcards
Recite the electromagnetic spectrum in order of decreasing wavelength
Radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x rays and gamma rays
What type of wave has the lowest frequency and energy, but largest wavelength
Radio waves
What do electromagnetic waves form
A continuous spectrum
Where do all types of electromagnetic waves travel at the same speed
All types of electromagnetic waves travel at the same speed through a vacuum (space)
What is the range of the wavelengths of the electromagnetic spectrum?
From 10^(-15) to 10^(4) metres
What type of light contains all the colours of the visible spectrum
White light contains all the colours of the physical spectrum
What do we use infrared radiation for
Carrying signals from remote handsets and inside optical fibres
What do we use microwaves for
Carrying satellite TV programmes and mobile phone calls
What do we use radio waves for
Radio and TV broadcasting, bluetooth
What is a danger with infrared radiation
Exposure can cause skin burns
What can exposure to ultraviolet cause
Skin cancer and blindness
What are x rays used for
Medical imaging
What are gamma rays used for
To kill harmful bacteria in food, to sterilise surgical equipment and to kill cancer cells
What and when do x rays and gamma rays damage
X rays and gamma rays damage living tissue when they pass through it
What are x rays used for in hospitals
To diagnose some medical conditions, for examiner in computed tomography (CT) scanning, bone fractures and dental problems. X rays are also used to treat some conditions, for example in killing cancer cells
What do CT scans distinguish between and how does this happen
Different types of soft tissue as well as between bone (or teeth) and soft tissue. This is because X rays are absorbed more by bones and teeth than by soft tissue
What is the frequency range of the normal human ear
From about 20Hz to 20,000Hz
What are sound waves
Sound waves are longitudinal waves and cause vibrations in a medium, which are detected as sound. They can be reflected (echoes) and diffracted
What are echoes caused by
Echoes are caused by sound waves reflected from a smooth, hard surface
The pitch of a note increases if the ………… Increases
The pitch of a note increases of the frequency of the sound waves increases
What increases the loudness of a sound
Increasing the amplitude of the sound wave
What produces sound waves
Vibrations created in a musical instrument when it is played produce sound waves
What is ultrasound
Ultrasound is acoustic (sound) energy, in the form of waves with a frequency above the human hearing range (20,000Hz)
What are ultrasound waves used for in medicine
Pre-natal scanning and the removal of kidney stones
What happens when ultrasound waves meet a boundary between two different media
Ultrasound waves are partially reflected when they meet a boundary between two different media
Why is an ultrasound scan safer than an x Ray
An ultrasound scan is non ionising, so it is safer than an X-ray
What type of wave has the smallest wavelength
Gamma rays
What types of waves can be used for communication
Radio waves, microwaves, infrared and visible light
Whats the hazard of exposure to microwaves
Heating of body tissue
What is a use of visible light
Photography
What is a use of ultraviolet
Security marking
What is the hazard of exposure to X rays
High doses kill cells
What can exposure to gamma rays cause
Genetic mutations
Characteristics of X rays
They have a very short wavelength, high energy and cause ionisation
What do properties of X rays include
-They affect a photographic film in the same way as light -They are absorbed by metal and bone -They are transmitted by soft tissue
What are the problems with the use of high energy ionising radiation, and what precautions therefore need to be taken
The use of high energy ionising radiation can be dangerous, and precautions need to be taken to monitor and minimise the levels of radiation that people who work with it are exposed to
How can you use ultrasound to determine how far away a boundary is
Ultrasound waves are partially reflected when they meet a boundary between two different media. They time taken for the reflections to reach a detector can be used to determine how far away such a boundary is (distance = [wave] speed x time)
What is the pitch of a sound determined by
Its frequency
What is the loudness of a sound determined by
Its amplitude
What can be used to produce ultrasound waves
Electronic systems
