What does it mean for an object to absorb or reflect light?

  • Thread starter no_audio
  • Start date
  • Tags
    Light Mean
In summary, when light shines on a green leaf, the electrons on its atoms are excited and emit photons with energy proportional to the frequency of the light. This is why the dominant wavelengths of these photons correspond to the color green. However, it is more accurate to say that leaves absorb green light rather than reflect it. This is because the electrons can only absorb photons with the exact energy needed to move them from one energy level to another. Additionally, leaves appear red under red light because they absorb the red light and do not reflect it. This is also why atomic absorption spectroscopy works. Molecules do not reflect light, they either reflect it coherently (reflect) or scatter it in random directions (scatter). When molecules absorb light,
  • #1
no_audio
4
0
Is it fair to say the following?

"When light shines on an object, say a green leaf, it excites electrons on the atoms of the leaf to go to higher energy levels. As the electrons fall back to lower energy levels, the atoms of the leaf emit photons with the energy E = hv where h is Planck's constant and v is the frequency of the emitted photon. The dominant wavelengths of these photons correspond to the color green in the visible light spectrum."

If the above is true, then why do we say that leaves are green because it reflects green light and absorbs everything else? Isn't it more accurate to say that leaves absorb green light? Also, if I took a leaf to a room with only red light, why does the leaf look red rather than black?

Along the same lines, is it true that electrons can only absorb photons with the exact energy needed to move electrons from one energy level to another (as in atomic absorption spectroscopy)?
 
Physics news on Phys.org
  • #2
reflect ::= molecules do not go excited, they just oscillate and at the same time emit the reflected wave, coherent with falling one

scatter ::= molecules got excited, but in a very short time they re-emit the light of the same wave (not-coherent with falling one) in random direction, returning 100% of the energy they got a moment before

absorb ::== molecules got excited by falling light then do something else with absorbed energy: just dissipate it thermally, use for photosynthesis...
 

Related to What does it mean for an object to absorb or reflect light?

1. What is the difference between an object that absorbs light and one that reflects light?

When an object absorbs light, it takes in the light energy and converts it into heat or another form of energy. This means that the object appears darker or less bright to our eyes. In contrast, an object that reflects light bounces the light off its surface, causing it to appear brighter or more colorful.

2. How does an object absorb light?

When light hits an object, it interacts with the atoms or molecules in the object. This interaction causes the energy from the light to be transferred to the particles, which then vibrate and heat up. This is why dark-colored objects can feel warmer in the sunlight than lighter-colored objects - they are absorbing more light energy.

3. Can all objects absorb light?

Yes, all objects have the ability to absorb at least some amount of light. However, the amount of light an object can absorb depends on its material and color. For example, a black object absorbs almost all light that hits it, while a white object reflects most of the light. This is why dark-colored objects are better at keeping heat than light-colored objects.

4. Why do some objects appear to change color when viewed under different lighting?

Objects appear to have different colors because of how they interact with different wavelengths of light. For example, a red apple appears red because it absorbs all colors of light except for red, which it reflects. Under a different light source with a different combination of wavelengths, the apple may appear to be a different shade of red or even a different color.

5. Is there a relationship between an object's color and its ability to absorb or reflect light?

Yes, there is a direct relationship between an object's color and its ability to absorb or reflect light. Objects that appear darker in color tend to absorb more light, while lighter-colored objects reflect more light. This is because the color of an object is determined by the wavelengths of light it reflects, while the rest of the wavelengths are absorbed.

Similar threads

Replies
1
Views
430
Replies
1
Views
1K
Replies
5
Views
1K
  • Quantum Physics
Replies
21
Views
896
  • Quantum Physics
2
Replies
38
Views
3K
Replies
1
Views
814
  • Quantum Physics
Replies
3
Views
1K
  • Quantum Physics
Replies
4
Views
2K
  • Quantum Physics
Replies
11
Views
1K
Replies
15
Views
1K
Back
Top