The Electromagnetic Spectrum Flashcards
What are the EM waves?
Radio-waves, Microwaves, Infra-red, Visible light, UltraViolet, X-rays, Gamma rays
What are the similarities of EM waves?
All transverse waves
Travel at the same speed through a vacuum
Unit for angles
Degree (°)
Unit for frequency
Hertz (Hz)
Unit for length
Metre (m)
Unit for speed/velocity
Metre/second (m/s)
Unit for time
Second (s)
Order EM waves from longest to shortest wavelength:
Radio-waves, Micro-waves, Infra-red, Visible Light, UltraViolet, X-Rays, Gamma Rays
Order EM waves from low to high frequency:
Radio-waves, Microwaves, Infra-red, Visible Light, UltraViolet, X-Rays, Gamma Rays
What are the order of colours in visible light?
Red, Orange, Yellow, Green, Blue, Indigo, Violet
What colour has the longest wavelength and the lowest frequency?
Red
What colour has the shortest wavelength and the highest frequency?
Violet
What are the uses of radio waves?
Broadcasting and communications
How does long-wave radio transmit?
Long-wave radio bends around the earth so they transmit over long distances (1km
How does short-wave radio transmit?
It reflects from the ionosphere (part of the atmosphere) so they can be received at long distances (100m)
What is the wave length of TV and FM radio waves?
Shortwave lengths (1m), need to be in direct sight of transmitter
What are the uses of microwaves?
Cooking and satellite transmissions
How does satellite transmission work?
Signal is transmitted from earth to orbit, satellite transmits signal to a satellite dish on earth
How are microwaves used for cooking?
Microwaves are absorbed by water molecules in food, it penetrates the food before being absorbed and conducted/ convected
What are the uses of Infra-red?
Heaters and night vision equipment
Is infrared given out by all objects?
IR is given out by all objects, the hotter the object the more IR given out
How does night vision equipment work?
IR is detected using the equipment which is turned into an electrical signal which can be displayed on screen
What are the uses of visible light?
Optical fibres and photography
How does optical fibres work?
Waves are bounced off the sides of a very narrow core
A pulse of light enters the fibre at a certain angle and reflects again and again until it emerges at the other end
What are the uses of Ultra Violet?
Fluorescent lamps
How do fluorescent lamps work?
UV light is absorbed by a chemical which emits visible light
What are the uses of X-Rays?
Observing the internal structure of objects and materials (medical applications)
What are the uses of Gamma rays?
Sterilising food and medical equipment
How does Gamma rays sterilise food?
It kills microbes - keeps food fresh for longer
How does Gamma rays sterilise medical equipment?
It kills all the microbes (better than boiling plastic instruments which may be damaged from high temperatures)
Which EM spectrum waves are dangerous?
Microwaves, Infrared, Ultraviolet, Gamma rays
What types of waves are usually more dangerous?
Waves with higher frequencies (they have more energy)
What damage can microwaves cause?
Internal heating of body tissue
How can you protect yourself against microwaves?
Microwave ovens have shielding to stop microwaves escaping
What damage can infrared cause?
It can cause skin burns
How can you protect yourself against microwaves?
Using insulating materials like oven gloves
What damage can ultraviolet cause?
It can cause skin cancer and blindness
How can you protect yourself against ultraviolet?
Avoid exposure to the sun and wear suncream
What damage can Gamma rays?
It can cause mutations and cancer
How can you protect yourself against gamma rays?
Store radioactive material in lead lined boxes
