Electromagnetic Spectrum Flashcards
4 properties of electromagnetic waves
- All electromagnetic waves are transverse waves that travel with the same speed in vacuum
- The speed of all electromagnetic waves in vacuum is 3 x 10^8 m s-1 in vacuum.
- The frequency of electromagnetic waves ranges from nearly 0Hz to 10^20Hz
- The wavelength of the waves can be calculated with the formula v = f入
7 main components of the electromagnetic spectrum
Radiowaves, microwaves, infrared, visible light, ultraviolet radiation, X-rays and gamma rays
How are radiowaves produced
They are produced from an AC in a tuned electrical circuit
Properties of radiowaves
They have long wavelengths and low frequencies.
Uses of radiowaves
- Radio and television communication
- Radiowaves of higher frequencies are used for rapid transfer of information in satellite TV because they can carry more information per unit time than radio waves of lower frequencies
- Radiowaves of lower frequencies are used in traditional radio stations.
How are microwaves produced
Microwaves are produced by oscillations of electrons in a vacuum.
Uses of microwaves
- Microwaves of 2450Hz are used in microwave ovens for cooking because it allows water molecules that have a natural frequency of 2450Hz to resonate with it. The water molecules then gain kinetic energy and increase in temperature to cook the food.
- Microwaves are also used to transfer data for satellite TV broadcasts and short-range internet links.
How is infrared produced
Infrared is radiation given out at a frequency of about 10^13 Hz, such as from bodies at room temperature.
Uses of infrared
- Television controls and intruder alarms
- Night vision binoculars to indicate the presence of warm objects when visible light is absent.
Range of frequencies of visible light
- violet: 380 - 450nm
- blue: 450 - 495nm
- green: 495 - 570nm
- yellow: 570 - 590nm
- orange: 590 - 620nm
- red: 620 - 750nm
Uses of visible light
- optical fibres for medical uses
- telecommunications
How is ultraviolet radiation produced
Ultraviolet radiation is produced by high energy electron transmissions
What is emitted from ultraviolet radiation
Ultraviolet light causes the emission of visible light from certain substances.
Uses of ultraviolet radiation
- sunbeds
- sterilisation in hospitals and science labs
How are x-rays produced
X-rays are produced from the collision of high energy electrons with a metal target
Properties of x-rays
X-rays have very high frequency, allowing it to pass through matter and affect photographic film
Uses of x-rays
- radiological and engineering applications, such as to reveal the insides of an object photographed with x rays
How are gamma rays emitted
Gamma rays are emitted when a nucleus loses energy after a nuclear reaction
Properties of gamma rays
Gamma radiation have frequency in the region of 10^20 Hz and energies in the order of the megaelectronvolt. Gamma radiation is even more penetrating than x-rays.
Uses of gamma rays
- medical treatment
Effects of absorbing radiowaves/microwaves
- causes slight heating when absorbed by the body but do not change the structures of the cells
- strong sources of radio signals could interfere with electronic devices such as pacemakers to malfunction
Effects of absorbing infrared radiation
- causes burns, only low levels of infrared radiation cause no harm
Effects of absorbing visible light (of high power)
Visible light with high power such as lasers can damage the eyes and burn the skin
Effects of absorbing ultraviolet radiation
- triggers the release of chemicals in the skin that causes redness and swelling that looks similar to a burn.
- can change the structure of the skin’s DNA and lead to skin cancer
Effects of absorbing x rays/gamma rays
- they possess enough energy to remove electrons from atoms in a process called ionization
- ionization of atoms part of a living cell can affect the ability of the cell to carry out its function or even rupture the cell wall.
- if a large number of cells which are part of a vital organ become affected, the organism could die
- therefore, exposure to x rays and gamma rays is limited.
