ElectroMagnegnetic Waves 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 is the wave speed equation
Wavelength (m) = speed (m/s) / frequency (Hz)
What do electromagnetic waves form
A continuous spectrum
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
…….. 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, radio communications and mobile phone calls
What are the hazards of micro waves and radio waves
They can heat the internal parts of our bodies
What is a danger with infrared radiation
Infrared radiation can cause skin burns
Radio waves of different frequencies are used for different purposes because wavelength (and therefore frequency) of waves effect:
How far they can travel
How much they can spread
How much information they can carry
Are mobile phones safe to use?
Further research is needed to evaluate this
What are optical fibres
Optical fibres are very thin transparent fibres that are used to transmit signals by light and infrared radiation
Ultraviolet radiation has a …………. Wavelength than visible light
Ultraviolet radiation has a shorter wavelength than visible light
What does ultraviolet radiation harm
The skin and the eyes
What are x rays used for
To make x Ray images in hospitals
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 make images and CT scans
To destroy tumours at or near the body surface
X rays are absorbed more by……..than by……..
X rays are absorbed more by bones and teeth than by soft tissue
What do CT scans distinguish between
Different types of soft tissue as well as between bone (or teeth) and 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 vibrations that travel through a medium (or substance). They cannot travel through a vacuum (outer space)
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 are ultrasound waves
Ultrasound waves are the sound waves of frequency above 20,000Hz
What are ultrasound waves used for in medicine
Ultrasound scanning and destroying kidney stones
When are ultrasound waves partly reflected
At a boundary between two different types of body tissue
Why is an ultrasound scan safer than an x Ray
An ultrasound scan is non ionising, so it is safer than an X-ray
