6.1, 6.2 and 6.3 The Electromagnetic Spectrum/Light, Infrared, Microwaves and Radio Waves/Communications Flashcards
What do electromagnetic waves do?
Transfer energy from one place to another
What does the amount of energy that electromagnetic waves transfer depend on?
The wavelength of the waves
What is the order of the electromagnetic spectrum?
Radio waves Micro waves Infrared radiation Visible light Ultraviolet lights X Ray Gamma ray
How fast do all electromagnetic waves travel?
300 million m/s
Describe the similarities and differences of the EM waves
Similarities:
Same wave speed
All travel through a vacuum
Differences:
Different wave lengths
Different frequencies
How do we group the EM waves?
According to their wavelength
Which type of rays have the shortest wavelength?
Gamma rays
Which type of EM waves have the highest frequency?
Gamma rays
What is the average wavelength of a gamma ray?
10 to the power of -15 m
Or
0.000000000000001
(14 0’s)
Which type of EM waves have the longest wavelength?
Radio waves
What type of EM waves have the lowest frequency?
Radio waves
What is the average wave length of a radio wave?
10,000m
What is the relationship between the frequency of an EM wave and the amount of energy it transfers?
The higher the frequency, the more energy it transfers
Why are the wavelengths and frequencies at the boundaries of the different EM waves approximate?
The different parts of the spectrum are not precisely defined
How do different surfaces react to the different wavelengths of the EM waves?
Different wavelengths of EM radiation are reflected, absorbed or transmitted differently by different substances and types of surface
Which part of the EM spectrum transfers the most energy?
Gamma rays
What are electromagnetic waves?
Electric and magnetic disturbances
Where can we emit radio waves from?
An alternating voltage applied to an aerial emits radio waves with the same frequency as the alternating voltage. When the waves are received, they create an alternating current in the aerial with the same frequency as the radiation received
Name 3 uses of radio waves
- TV
- radio
- mobile phone
Name a danger of radio waves used in mobile phones
•radiation on the phone can cause damage to our brains
What else gives off radio waves naturally?
Stars and lightning
What can the frequencies of radio waves range between?
300,000Hz to 3 billionHz
Where can micro waves be emitted from?
Satellites and pass through the atmosphere
Name 2 uses of micro waves
- satellite TV
* mobile phones
Name a danger of micro waves used in mobile phones
Radiation on phone could cause damage to our brains
Which waves spread out more: radio or micro?
Radio waves
Where is infrared radiation emitted?
All objects emit infrared radiation
Name 3 uses of infrared radiation
- optical fibres
- remote controls
- infrared scanners/cameras
Name a danger of infrared radiation
•absorbed by the skin so can be dangerous to skin cells if they are heated too much and can be destroyed
What is the relationship between the heat of an object and the amount of infrared radiation it emits?
The hotter the object is, the more infrared radiation it emits
Name 2 sources of visible light
- the sun
* ordinary lamps
Name two uses of visible light
- lamps
* light bulbs
Name 2 dangers of visible light
- sun can cause blindness
* sun burn can cause cancer
Where is ultraviolet radiation emitted from?
Stars
Name 3 uses of ultraviolet radiation
- to check bank notes
- suntan
- nail salon
Name 2 dangers of ultraviolet radiation
- sun burn
* skin cancer
Name 2 sources of x rays and gamma rays
- stars
* X-Ray machines
Name 2 uses of X-rays and gamma rays
- airport security
* hospitals
What EM waves are the most dangerous and why?
Gamma rays because they have the highest frequency
Name a danger of X-rays and gamma rays
•causes cancer
What do we see the different wavelengths of visible light as?
Different colours
Which colour has the lowest wavelength?
Violet
Which colour has the biggest wavelength?
Red
Why is micro wave and radio wave radiation dangerous for us?
They penetrate our skin and are absorbed by body tissue, this can heat your internal organs and damage them
What is the radio wave and microwave spectrum split into?
Different bands, decided by the different communication purposes
What does a shorter wavelength mean for the amount of information it carries, their range and the amount they spread out?
The shorter the wavelength
•the more information they carry
•the shorter their range
•the less they spread out
What type of EM wave lets your phone transfer information to a local mobile phone mast?
Micro waves
What are optical fibres and what are they used for?
Very thin glass fibres used to transmit signals carried by visible light or infrared radiation
How does a signal travel down the optical fibre?
Total internal reflection
Why are optical fibres useful in communications?
They carry much more information and are more secure than micro waves as they use visible light and infrared which both have shorter wavelengths
