P2.2/3 - Infrared Radiation Flashcards
infrared radiation
electromagnetic waves between visible light and microwaves in the electromagnetic spectrum
How are conduction/convection different from infrared radiation?
- conduction/convection involves the heat transfer through particles
- infrared doesn’t involve particles
Electromagnetic waves
- are electric/magnetic waves
- travel through space
Wavelength comparison of infrared and visible light
-infrared has a longer wavelength than visible light
The light bulb is an example of what part of the electromagnetic spectrum
visible light spectrum
How are waves sorted in the electromagnetic specturm?
in order of their wavelengths
Do all waves in the electromagnetic travel at the same speed?
- yes
- at the speed of light through a vacuum
- 300 million m/s
White light is made up of what colours?
- Red
- orange
- yellow
- green
- blue
- violet
where is infrared located on the electromagnetic spectrum
next to red in the visible light spectrum
Do all objects emit and absorb infrared?
- yes
- despite their temp
The hotter an object..
the more infrared they emit
A body at a constant temperature…
emits infrared at the same rate as it absorbs it at
Hotter objects emit radiation…
at a higher intensity
Absolute zero of an object
- no kinetic energy of particles in object
- so cannot absorb/emit
A perfect black body:
- absorbs all radiation that hits it
- doesn’t reflect or transmit
- no other object emits/absorbs as well as this body
transmit meaning
allow to pass through
Radiation emitted by the black body is called?
black body radiation
A good emitter is also..
a good absorber
An object that has a constant temperature…
emits radiation across a continuous range of wavelengths
In a black body graph, explain the difference between higher radiation curve and the lower curve?
-the higher radiation curve has a shorter wavelength
Why does the higher radiation curve in a black body graph have a shorter wavelength?
- as the shorter wavelength,
- causes a greater increase in intensity of radiation
If an object has a constant temperature..
the object emits infrared at the same rate it absorbs it at.
When an object absorbs radiation faster than it emits it…
the temperature increases
Earth’s temp depends on
- the rate that light or infrared from the sun are
- reflected back into space or absorbed into the atmosphere
- emitted from the Earth’s surface/atmosphere into space
What would happen if the Earth had no temperature?
- its temp would plunge
- as it would not be absorbing but only emitting radiation into space
Process of the Earth being heated by the sun
- Infrared from the sun warms the Earth’s ground
- Ground becomes hot and emits longer wavelength infrared
- CO2 absorbs and re-emits this infrared into the ground
The hotter the object…
the shorter the wavelengths of the infrared it emits
