Infared Radiation & black body Flashcards
What objects absorb and emit radiation
Every object
When does an object radiate more radiation in a given time
The hotter the object is
When will an object emit more radiation than it absorbs
And what does this mean is happening
When the object is hotter than its surrounding
This means it will be cooling down
When will an object warm up
When the object is cooler than its surroundings and so will absorb more inflated radiation than it emits
What colour surfaces are better at emitting and absorbing radiation
Black is better than white
What experiment investigates the amount of absorbtion by different materials
The melting wax trick
How do you investigate emission of materials
With a Leslie cube
What is a Leslie cube
A hollow water light metal cube made of something like aluminium which surface has 4 different surfaces
What do you do with a Leslie cube
fill it up with boiling water
Make sure all the 4 surfaces are te same temp
Hold an infrared detected a set distance from each of the surfaces and record how much infrared it’s emitting
What is a perfect black body
An object that absorbs all of the radiation that hits it
No radiation is reflected or transmitted
What does the intensity and distribution of the wavelengths emitted by an object depend on
The objects temperature
What is intensity measured by
The power per unit area
How much energy is transferred to a given area in a certain amount of time
What happens to emitted wavelengths when the temperature of an object increases
The intensity of every emitted wavelength increases
What is the peak wavelength
The wavelength with the highest intensity
And it decreases when an object gets hotter
What does the overall temp of the earth depend on
Eh amount of infrared radiation it reflects absorbs and emits
