P5.2 - The Electromagnetic Spectrum Flashcards
Give properties of EM radiation.
- EM stands for electromagnetic.
- EM radiation is energy.
- EM radiation travels as a transverse wave.
- EM radiation doesn’t transfer matter - It is a
transverse wave. - The electric field, magnetic field and direction of
energy transfer are all parallel to each other. - EM radiation can travel in a vacuum as it doesn’t
require particles. - EM radiation is just different frequencies of light.
What must happen in order to produce a wave of any kind?
In order to produce a wave of any kind, something must initially oscillate/vibrate.
What is the speed of EM waves through a vacuum?
3.0 x 108m/s
What is the electromagnetic spectrum?
The EM spectrum is a continuous range of all possible frequencies/wavelengths of EM radiation.
What happens as the frequency of EM radiation increases?
- As the frequency of EM radiation increases, the
energy of EM radiation increases. - High energy EM radiation has small
wavelengths.
What is the amplitude of EM radiation a measure of?
Amplitude of EM radiation is a measure of the light
intensity (energy) - How much light is arriving in a given time over a given area.
Give the sources of EM radiation in order of increasing frequency including the visible light spectrum.
Radio waves I Richard - Red
Microwaves I Of - Orange
Infrared I York - Yellow
Visible light ————– I Gave - Green
Ultraviolet I Battle - Blue
x-rays I In - Indigo
Gamma rays I Vain - Violet
How are radio waves produced?
- An oscillating potential difference is applied
across a wire. - Electrons oscillate backwards and forwards at the
same frequency. - Produces oscillating electrostatic and magnetic
fields. - These fields travel and cut across an aerial.
- Electrons inside the aerial oscillate, producing an
electric signal.
What are the properties of radio waves?
- Easily pass through air and solids.
- Can be used for radio and tv signals.
- No hazards.
What are the properties of microwaves?
- Easily pass through air and Earth’s atmosphere.
- Can be used for cooking food, mobile phones
and satellites - Can heat up water which is a possible risk to
humans.
What are the properties of infra-red waves?
- Pass through air and glass but stopped by solids.
- Can be used for night vision and remote controls.
- Absorbed by skin which causes it to heat up.
What are properties of light?
- Passes through air and glass but is stopped by
solids. - Can be used to see cameras.
- Can have a very high amplitude and be very
bright.
What are the properties of ultraviolet waves?
- Moderately penetrates Earth’s atmosphere but
can’t penetrate the skin. - Can be used to produce vitamin D, detects bodily
fluids and kills bacteria in water. - Somewhat ionising which can damage skin cells
leading to skin cancer.
What are properties of X-Rays?
- Penetrates skin and thin metals but are stopped
by bone and dense metals. - Can be used for X-ray imaging and treatment of
some cancers. - Lightly ionising - likely to damage cells and give
rise to cancer
What are properties of gamma waves?
- Penetrates most material but is stopped by very
thick lead. - Can be used for treatment of cancer and the
sterilisation of medical instruments. - Quite ionising - likely to damage cells and give rise
to cancer.
Describe how infrared radiation is used for imaging.
- Thermal imaging cameras use infrared radiation
to produce thermograms. - A charged coupled device (CCD) absorbs the
infrared radiation and displays it as visible
colour. - Different colours of visible light are used to
indicate the different intensities of infrared
radiation. - The hotter a certain part of a medium, the more
infrared light it will emit.
Describe how X-ray radiation is used for imaging.
- X-rays produce images by showing contrast
(differences in shades) between two media. - In hospitals, X-rays are used to irradiate a person’s
body. - X-rays will pass through soft tissue (low density
medium) but are absorbed by bone (high density
medium) . - X-rays that pass through the body, darken
photographic film. - The film remains white where X-rays were
absorbed by the body and didn’t reach the film.
Describe how gamma radiation is used for imaging.
- A radioactive tracer is a radioactive compound
of an element. - Radioactive tracers will (usually) emit gamma
radiation. - Radioactive tracers are ingested by/injected
into a patient and quickly enter the bloodstream
and organs. - The intensity of the gamma radiation being
emitted is monitored outside by a camera. - Where there is poor blood flow inside the body,
less gamma radiation will be emitted there, and
this indicates a possible health problem.
