Radiation & Heat Flashcards
(33 cards)
What’s the average surface temp of our planet?
14.5C
Kelvin = Celsius + 273.15
- the average surface temp of our planet in K = 288 K
What is heat
the transfer of energy
What is energy
the capacity for doing work
What is entropy
the capacity for chaos (measure of disorder)
What is radiation
the transfer of energy between the Earth and the Sun
What are the 2 laws of thermodynamics
Law of Conservation
Law of Flows
Every object that has a temperature above ___ Kelvin is emitting energy
zero
What is steady state?
the planet is keeping some portion of the Energy coming in with excess energy flowing out
a fundamental way in which light moves from one location to another
What is Electromagnetic Radiation
What are the 2 conceptual models for light?
Wave description
Particle description
speed is ______ but the wavelength ________
constant ; varies
Wave description
light behaves as a wave
- composed of oscillating electric and magnetic fields
- arise from the motions of electrical charges
Particle description
light consists of streams of particle-like entities called “photons”
If molecules have the same oscillation as radiation ______, they can interact with each other (known as the _________) and cause the atom to become more ________ .
light ; greenhouse effect ; energetic
All _________ travels at the speed of light
radiation
What is Electromagnetic radiation
refers to the fact that when energy is transferred through a wave property in which there is matter (i.e. molecules) it can interact with that mass
Blackbodies
a perfect absorber and a perfect emitter of radiation that emits the maximum amount of radiation and absorbs all the radiation reaching it
What determines the temperature of a blackbody?
the amount of radiation being absorbed minus the amount of radiation being emitted
What is Planck’s Law
objects at higher temps (like the sun) emit most of their energy at shorter wavelengths (UV and Visible). objects at colder temps (like the Earth) emit most of their energy in the longer wavelengths
Most radiation is emitted from the sun at the ______ and ________ region.
visible ; UV
What is the Stefan Boltzmann Law
the total energy flux emitted by a blackbody across all wavelengths is proportional to the 4th power of the absolute temp of the object
What law tells us how much energy is being given off per area?
Stefan Boltzmann Law
What is the surface area of the sun?
6.07 x 10^18
if the temp is ________, then a body emits zero radiation
zero
