What energy exactly does photosynthesis extract from sunlight?
October 18th, 2009 | by Michael |
Lalen asked:
Photosynthesis, the biological conversion from light energy to chemical energy… But I thought photons have zero mass (therefore zero energy?), so where is this energy coming from? Does it just refer to the extremely small energy that comes from a photon’s momentum?
JONAS
Photosynthesis, the biological conversion from light energy to chemical energy… But I thought photons have zero mass (therefore zero energy?), so where is this energy coming from? Does it just refer to the extremely small energy that comes from a photon’s momentum?
JONAS
5 Responses to “What energy exactly does photosynthesis extract from sunlight?”
By Alihusen K on Oct 20, 2009 | Reply
Energy conversion takes place due to exited (which get exited due to sunlight) molecules present in the chlorophyll of a leaf. Energy due to photons is also there but in a negligible amount.
By AxisOfIntolerance on Oct 22, 2009 | Reply
it is the energy from a photon of visible light, which is absorbed promoting an electron to a higher energy state allowing it to initiate a series of chemical reactions.
you are correct, but a photon does have mass, just not like you’re thinking:
relativistic mass is energy, the photon is energy and it is absorbed by the chlorophyll molecule. You are thinking of
e = mc^2 of relativity. The nucleas of an atom has a mass less than the sum of the individual protons and neutrons that make it up, this difference in mass is the energy that holds the nucleas together, it is realeased in a nuclear reaction as light, in your case sunlight.
check out these questions:
By El fagguito on Oct 24, 2009 | Reply
Photons have energy even if they dont have mass (rest mass). Both subjects are not directly related.
The energy of a photon is calculated as Energy=frecuency*plank constants and is usally measured in electronvolts. The average photon in solar radiation has an energy of 1.5 electronvolts.
Again, no mass is required.
By Louis S on Oct 27, 2009 | Reply
is it photons or electrons?
By draco4843 | on Oct 30, 2009 | Reply
There seems to be a misconception in your statement. The photon is a boson particle and therefore has mass. But the reference to the mass of a photon is not used as it would result in an ambiguity or conflict with Relativistic Physics. Energy therefore is used to describe a photon and is given by the equation;
E = hv
Where;
E = the energy of the photon
h = Planck’s constant
v = frequency
The above shows that electromagnetic radiations have specific energies which are not extremely small. Just consider that considerable amount of energy can be generated by solar cells.
Now going back to photosynthesis. The green leaves of plants absorb all other colors of visible light except green. Green is the one that is reflected and that is what you see with your eyes.
The energy of the light that is absorbed causes reactions of carbon dioxide with other chemicals in the cells of the leaves resulting in the production of food.