What is a form of evolution that is also known as adaptive radiation?What is a form of evolution that is also known as adaptive radiation?
Darwin finches.
Saturday, March 10, 2012
Temperature on earth if radiation off earth equals radiation recieved from the sun?
What would the temperature on earth be if we assume that its temperature makes the outgoing radiation equal to the radiation vi receive from the sun? The earth is not a perfect black-body and some of the the outgoing radiation will be reflected by the atmosphere.
The power density of the sun's radiation on the surface of the earth is approximately 1.4 kW/m^2 when the radiation is perpendicular to the ground.
And in addition, what would the earth temperature be if we had sunlight 24 hours a day everywhere on earth?
Pointers or complete solutions would be greatly appreciated.Temperature on earth if radiation off earth equals radiation recieved from the sun?
The idea is the following: the total power emission of a black body is P = s T^4 where s is the stefan boltzmann constant. Thus, the sun, which we can imagine to be at the center of the earth's circular orbit radiates a power s T^4. now if we assume the radiation is isotropic (independent of direction) how much power is incident on the earth? consider the energy flux (power/unit area) emitted from the sun, ie imagine the power radiating like a big sphere from the surface of the sun- for power to be conserved the power density must decrease like 1/r^2 where r is the distance from the sun. so the power density at a distance R from the sun is
p = P/A = s T^4 / (4 pi R^2)
this power density p is incident on the earth's cross section, and so the total power absorbed by the earth is
p * pi re^2
where re is the radius of the earth. the earth will be at thermal equilibrium when it is also emitting this much power
ie when
Pe = s Te^4 = s T^4 (pi re^2) / (4pi R^2)
where Te is the temperature of the sun. So just solve for Te!
The power density of the sun's radiation on the surface of the earth is approximately 1.4 kW/m^2 when the radiation is perpendicular to the ground.
And in addition, what would the earth temperature be if we had sunlight 24 hours a day everywhere on earth?
Pointers or complete solutions would be greatly appreciated.Temperature on earth if radiation off earth equals radiation recieved from the sun?
The idea is the following: the total power emission of a black body is P = s T^4 where s is the stefan boltzmann constant. Thus, the sun, which we can imagine to be at the center of the earth's circular orbit radiates a power s T^4. now if we assume the radiation is isotropic (independent of direction) how much power is incident on the earth? consider the energy flux (power/unit area) emitted from the sun, ie imagine the power radiating like a big sphere from the surface of the sun- for power to be conserved the power density must decrease like 1/r^2 where r is the distance from the sun. so the power density at a distance R from the sun is
p = P/A = s T^4 / (4 pi R^2)
this power density p is incident on the earth's cross section, and so the total power absorbed by the earth is
p * pi re^2
where re is the radius of the earth. the earth will be at thermal equilibrium when it is also emitting this much power
ie when
Pe = s Te^4 = s T^4 (pi re^2) / (4pi R^2)
where Te is the temperature of the sun. So just solve for Te!
Is it normal for curly hair to grow back straight after radiation therapy?
I had IMR radiation for 6 weeks after having a brain tumour removed (2 years ago Jan. '11) MY hair has, for the most part, all grown back now. The hairline around my ears changed a bit, but what I'm noticing most is that my hair is relatively straight now. Before starting radiation it was curly, to the point of unmanageable. I was just wondering if it was normal for radiation to affect hair this way. Thanks!Is it normal for curly hair to grow back straight after radiation therapy?
Yes it is normal for treatments to change the texture and color of your hair.Is it normal for curly hair to grow back straight after radiation therapy?
mine was the opposite. after my chemo treatment, my hair was incredibly curly, and before it was straight. now a year and a half off its back to normal.north carolina dmv acura tsx
Yes it is normal for treatments to change the texture and color of your hair.Is it normal for curly hair to grow back straight after radiation therapy?
mine was the opposite. after my chemo treatment, my hair was incredibly curly, and before it was straight. now a year and a half off its back to normal.
Is it normal for curly hair to grow back straight after radiation therapy?
I had IMR radiation for 6 weeks after having a brain tumour removed (2 years ago Jan. '11) MY hair has, for the most part, all grown back now. The hairline around my ears changed a bit, but what I'm noticing most is that my hair is relatively straight now. Before starting radiation it was curly, to the point of unmanageable. I was just wondering if it was normal for radiation to affect hair this way. Thanks!Is it normal for curly hair to grow back straight after radiation therapy?
Yes it is normal for treatments to change the texture and color of your hair.Is it normal for curly hair to grow back straight after radiation therapy?
mine was the opposite. after my chemo treatment, my hair was incredibly curly, and before it was straight. now a year and a half off its back to normal.
Yes it is normal for treatments to change the texture and color of your hair.Is it normal for curly hair to grow back straight after radiation therapy?
mine was the opposite. after my chemo treatment, my hair was incredibly curly, and before it was straight. now a year and a half off its back to normal.
What is a good title for a research paper about cellphone radiation's harmful biological effects?
We are conducting a research about exposure to cellphone radiation as a cause for harmful biological effects such as brain cancer, dizziness and etc..What is a good title for a research paper about cellphone radiation's harmful biological effects?
"An Invisible killer beside you"
"a portable cance"What is a good title for a research paper about cellphone radiation's harmful biological effects?
"Sending Messages (and Radiation)"
"Unhealthy Phone Calls?"
"Talking Your Way to Cancer?"
"An Invisible killer beside you"
"a portable cance"What is a good title for a research paper about cellphone radiation's harmful biological effects?
"Sending Messages (and Radiation)"
"Unhealthy Phone Calls?"
"Talking Your Way to Cancer?"
What is the importance of atmospheric ozone in terms of ultraviolet radiation from the sun?
What is the importance of atmospheric ozone in terms of ultraviolet radiation from the sun?What is the importance of atmospheric ozone in terms of ultraviolet radiation from the sun?
Ozone is made because the nitrogen and oxygen in the "ozone layer" stop UV-C and more energetic radiation from the Sun.
DNA-based life exists on the surface of the Earth because ozone blocks most UV-B from the Sun.
Ozone is made because the nitrogen and oxygen in the "ozone layer" stop UV-C and more energetic radiation from the Sun.
DNA-based life exists on the surface of the Earth because ozone blocks most UV-B from the Sun.
What is the behaviour that supports the dual nature of electromagnetic radiation?
Electromagnetic radiation (i.e. infra red and so on) have a wave-particle duality meaning it can behave as a wave or as a photon (that exhibits particle-like behaviour), I want to know the behaviour that they exhibit that supports this theory...can anyone help?What is the behaviour that supports the dual nature of electromagnetic radiation?
Young's slit experiment:
http://www.youtube.com/watch?v=pSHlp9z3n…
http://www.youtube.com/watch?v=RlPvzn5sG…
Photoelectric effect, slightly more complex.
The principle behind the Photoelectric effect basically is that if light is a wave then the only factor which should affect the amount of electrons escaping the electrostatic attraction of the metal should be the amplitude (i.e. the amount of energy in the wave) but not the frequency of the wave- doesn’t matter how many times you hit a lorry with a hammer, its never going to move. Also, if the light waves amplitude is too low, then you get no electrons escaping from the electrostatic force, because the waves won’t transfer enough energy to liberate them themselves. But…
Planck’s constant, which is referred to as h, and apparently h=6.626x10^(-34)Joules,
showed that energy could only come in discrete energy ‘packets’, which lead Einstein to believe that light also came in discrete energy packets, which would mean that light itself would be a particle- a photon. The amount of energy transferred would be Planck’s constant times the frequency of the photon (because frequency is proportional to the energy level) which would mean that frequency of the electromagnetic radiation would affect the kinetic energy of electrons escaping from the electrostatic force, because the photons with higher frequencies would have more energy, and so transfer more. This would mean that leaving the intensity (the amount of photons hitting the surface per unit of time) the same, but increasing the frequency of the light, would raise the maximum kinetic energy level of the electrons which are liberated, and that leaving the frequency constant, and increasing the intensity of the light would mean more electrons would be released, but their kinetic energy would remain constant. This would also mean that electromagnetic radiation with too low a frequency would not liberate any electrons, but that if you have a really high frequency, even if you have very low intensity, then you will still liberate some electrons.
Robert Andrews Millikan conducted experiments in 1910s which has since verified all of the predictions set out by the photoelectric effect.
However, light can not be just a particle, as certain aspects of it have been proved to be wave, or wave-like, namely in the “double-slit experiment”, but many others as well.
This is the site I used. Its got to be the best for clarity,
http://www.colorado.edu/physics/2000/qua…
good luck :DWhat is the behaviour that supports the dual nature of electromagnetic radiation?
in explaining the phenomena like interference ,diffraction ,polarisation light is treated as a wave where as it is treated as a photon to explain photoelectric effect , compton effect.What is the behaviour that supports the dual nature of electromagnetic radiation?
Hope this helps.
A time-domain method with isotropic dispersion and increased stability on an overlapped lattice
Forgy, E.A. Weng Cho Chew
Dept. of Electr. %26amp; Comput. Eng., Illinois Univ., Urbana, IL;
This paper appears in: Antennas and Propagation, IEEE Transactions on
Publication Date: Jul 2002
Volume: 50, Issue: 7
On page(s): 983- 996
ISSN: 0018-926X
INSPEC Accession Number: 7370039
Digital Object Identifier: 10.1109/TAP.2002.801373
Posted online: 2002-11-07 17:09:07.0
Abstract
A time-domain method on an overlapped lattice is presented for the accurate and efficient simulation of electromagnetic wave propagation through inhomogeneous media. The method comprises a superposition of complementary approximations to electromagnetic theory on a lattice. The discrete space-time (DST) method, is set on a pair of dual lattices whose field components are collocated on their respective lattice sites. The other, the time-domain element (TDE) method, is set on overlapping dual lattices whose field components are noncollocated. The TDE method is shown to be a generalization and reinterpretation of the Yee algorithm. The benefits of the combined algorithm over comparable methods include: (1) increased accuracy over larger bandwidths; (2) increased stability allowing larger time steps; (3) local stencil-satisfying boundary conditions on interfaces; (4) self-contained mathematical framework; (5) it is physically intuitive.
Enjoy
Young's slit experiment:
http://www.youtube.com/watch?v=pSHlp9z3n…
http://www.youtube.com/watch?v=RlPvzn5sG…
Photoelectric effect, slightly more complex.
The principle behind the Photoelectric effect basically is that if light is a wave then the only factor which should affect the amount of electrons escaping the electrostatic attraction of the metal should be the amplitude (i.e. the amount of energy in the wave) but not the frequency of the wave- doesn’t matter how many times you hit a lorry with a hammer, its never going to move. Also, if the light waves amplitude is too low, then you get no electrons escaping from the electrostatic force, because the waves won’t transfer enough energy to liberate them themselves. But…
Planck’s constant, which is referred to as h, and apparently h=6.626x10^(-34)Joules,
showed that energy could only come in discrete energy ‘packets’, which lead Einstein to believe that light also came in discrete energy packets, which would mean that light itself would be a particle- a photon. The amount of energy transferred would be Planck’s constant times the frequency of the photon (because frequency is proportional to the energy level) which would mean that frequency of the electromagnetic radiation would affect the kinetic energy of electrons escaping from the electrostatic force, because the photons with higher frequencies would have more energy, and so transfer more. This would mean that leaving the intensity (the amount of photons hitting the surface per unit of time) the same, but increasing the frequency of the light, would raise the maximum kinetic energy level of the electrons which are liberated, and that leaving the frequency constant, and increasing the intensity of the light would mean more electrons would be released, but their kinetic energy would remain constant. This would also mean that electromagnetic radiation with too low a frequency would not liberate any electrons, but that if you have a really high frequency, even if you have very low intensity, then you will still liberate some electrons.
Robert Andrews Millikan conducted experiments in 1910s which has since verified all of the predictions set out by the photoelectric effect.
However, light can not be just a particle, as certain aspects of it have been proved to be wave, or wave-like, namely in the “double-slit experiment”, but many others as well.
This is the site I used. Its got to be the best for clarity,
http://www.colorado.edu/physics/2000/qua…
good luck :DWhat is the behaviour that supports the dual nature of electromagnetic radiation?
in explaining the phenomena like interference ,diffraction ,polarisation light is treated as a wave where as it is treated as a photon to explain photoelectric effect , compton effect.What is the behaviour that supports the dual nature of electromagnetic radiation?
Hope this helps.
A time-domain method with isotropic dispersion and increased stability on an overlapped lattice
Forgy, E.A. Weng Cho Chew
Dept. of Electr. %26amp; Comput. Eng., Illinois Univ., Urbana, IL;
This paper appears in: Antennas and Propagation, IEEE Transactions on
Publication Date: Jul 2002
Volume: 50, Issue: 7
On page(s): 983- 996
ISSN: 0018-926X
INSPEC Accession Number: 7370039
Digital Object Identifier: 10.1109/TAP.2002.801373
Posted online: 2002-11-07 17:09:07.0
Abstract
A time-domain method on an overlapped lattice is presented for the accurate and efficient simulation of electromagnetic wave propagation through inhomogeneous media. The method comprises a superposition of complementary approximations to electromagnetic theory on a lattice. The discrete space-time (DST) method, is set on a pair of dual lattices whose field components are collocated on their respective lattice sites. The other, the time-domain element (TDE) method, is set on overlapping dual lattices whose field components are noncollocated. The TDE method is shown to be a generalization and reinterpretation of the Yee algorithm. The benefits of the combined algorithm over comparable methods include: (1) increased accuracy over larger bandwidths; (2) increased stability allowing larger time steps; (3) local stencil-satisfying boundary conditions on interfaces; (4) self-contained mathematical framework; (5) it is physically intuitive.
Enjoy
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