thermal energy transfers

Created by

Leah beyram

Cards (35)

what is absolute zero
the temperature at which the molecules in a substance have zero kinetic energy
what does the average random kinetic energy of particles tell is about the absolute temperature
it is directly proportional to the average kinetic energy
what is internal energy
the sum of the kinetic energy and potential energy
how do you calculate the average random kinetic energy of particles  
Ek = 3/2 x kB x T
what does the average random kinetic energy of particles tell us
the absolute temperature of a body is directly proportional to the average kinetic energy of the molecules
what happens when thermal energy is transferred to a substance
increase in kinetic energy, increase of potential energy
what happens when only the potential energy of the molecules changes  
the temperature of the substance does not change
what is thermal equilibrium  
when two substances in contact with each other no longer exchange any heat energy and both reach an equal temperature
what must happen for thermal equilibrium to occur  
two regions need to be in thermal contact
how can thermal energy be transferred
conduction, convection and radiation
what is conduction  
when two different temperatures come in contact with one another, hotter to cooler
how can conduction occur  
atomic vibrations and free electron collisions
what is thermal conductivity  
the ability of a substance to transfer heat via conduction
what is a temperature gradient  
when thermal energy flows from the region of higher temperature to the region of lower temperature
what is convection  
when a fluid is heated causing the movement of groups of atoms or molecules due to variations in density
what happens during convection
convection current is made
what is thermal radiation
when heat is transferred by means of electromagnetic radiation normally in the infrared region
what does the amount of thermal radiation emitted by an object depend on
the surface colour, the texture of the surface and the surface area
what is black-body radiation  
the name given to the thermal radiation emitted by all bodies
what is a perfect black-body  
an object that absorbs all of the radiation incident on it without any being reflected or transmitted
what does the intensity and wavelength of any emitted wave depend on
the temperature of the body
what type of visible light is emitted in objects around 1000C
red
what type of visible light is emitted in objects around 6000C
white or blue
what is apparent brightness of a star  
the intensity of radiation received on Earth from a star
what does apparent brightness depend on
how much light is emitted, how far the star is
what is luminosity  
the total power output of radiation emitted by a star
what does luminosity tell us  
how bright the star is at its surface
what does apparent brightness tell us
how bright the star is as observed from Earth
what is the inverse square law 
light sources which are farther away appear fainter because the light emitted is spread out over a greater area
what does the inverse square law equation assume
the power from the star is radiated uniformly through space, no radiation is absorbed between the star and the Earth
what does the inverse square law equation tell us  
luminosity is constant
intensity of the emitted light follows the inverse square law for stars with the same luminosity, the star with the greatest apparent brightness is close to Earth
what is Stefan-Boltzmann's law  
the total energy emitted by a black-body per unit area per second is proportional to the fourth power of the absolute temperature
what is Wien's displacement law
the black-body radiation curve for different temperatures peaks at a wavelength that is inversely proportional to the temperature
what does Wien's law equation show us about bodies with higher temperatures  
they have shorter wavelengths at the peak intensity
hotter objects tend to be white or blue
cooler objects tend to be red or yellow
they have a greater intensity of radiation at each wavelength
what must you do if you are using the Wien's law equation c
convert to kelvin