Absorption of light in a mirror

Click For Summary
SUMMARY

No mirror is 100% reflective; all mirrors absorb some light regardless of their design. While a perfectly reflective mirror would theoretically absorb no light, such mirrors do not exist in practice. Mirrors made from materials like aluminum, gold, and silver reflect different portions of the electromagnetic spectrum, with aluminum being optimal for visible light and gold for near-infrared light. The absorption characteristics vary based on the wavelength, with mirrors appearing greenish from the side due to differential absorption of wavelengths.

PREREQUISITES
  • Understanding of electromagnetic spectrum and wavelengths
  • Familiarity with materials used in mirror production (e.g., aluminum, gold, silver)
  • Knowledge of reflectivity and absorption principles
  • Basic optics concepts related to light reflection
NEXT STEPS
  • Research the properties of aluminum mirrors for visible light applications
  • Explore the reflectivity of gold and silver mirrors in near-infrared applications
  • Study the impact of different materials on light absorption and reflection
  • Investigate the optical characteristics of mirrors across various wavelengths
USEFUL FOR

Physicists, optical engineers, material scientists, and anyone interested in the principles of light reflection and absorption in mirrors.

richardz03
Messages
12
Reaction score
0
I read in some place that the mirror be it 100 per cent reflective, will also absorb if a light strikes to it. Is it true? what does it absorbs?
 
Last edited by a moderator:
Science news on Phys.org
No mirror is 100% reflective, so yes, some amount of light will be absorbed no matter what. A perfectly reflective mirror would, by definition, reflect 100% of the light and absorb none. But these do not exist.
 
Drakkith said:
No mirror is 100% reflective, so yes, some amount of light will be absorbed no matter what. A perfectly reflective mirror would, by definition, reflect 100% of the light and absorb none. But these do not exist.

Ok but what does it absorbs? does it absorbs all the color a little bit or something else happens
 
richardz03 said:
I read in some place that the mirror be it 100 per cent reflective, will also absorb if a light strikes to it. Is it true? what does it absorbs?

This doesn't quite make any sense, does it? If it is 100% reflective, then there is no absorption.

What exactly are you asking here? Are you asking on what happened to the light that is not reflected in a typical mirror? Or are you asking for something else?

Zz.
 
It will absorb a little bit of all the wavelengths. Mirrors can be made from many different materials to enhance their reflectivity of certain parts of the EM spectrum. For example, mirrors designed to reflect near-infrared light are typically made of gold because it reflects a larger portion of near IR light than most other kinds of mirrors. Aluminum is typically used to make visible light mirrors since it reflects a significant portion of visible light that falls on it, but will reflect less of other types of EM radiation such as UV or IR (it's also much cheaper than most alternative materials).

See the graph below, which comes from here: http://en.wikipedia.org/wiki/Reflectivity

400px-Image-Metal-reflectance.png


As you can see, the amount of light reflected (measured by the Y-axis) changes depending on the wavelength and the type of mirror. Note that visible light has a wavelength between 400 nm to 700 nm. In this range the aluminum (Al) mirror reflects more light than the other two. Gold (Au) and silver (Ag) reflect more light in the near-IR range which is the right half of the graph.
 
Just FYI, posts from another thread have been merged into this one.
 
Drakkith said:
As you can see, the amount of light reflected (measured by the Y-axis) changes depending on the wavelength and the type of mirror. Note that visible light has a wavelength between 400 nm to 700 nm. In this range the aluminum (Al) mirror reflects more light than the other two. Gold (Au) and silver (Ag) reflect more light in the near-IR range which is the right half of the graph.
Aluminium also reflects different wavelengths more evenly, so the reflections appear in the same colors as the original.

As seen from the side, mirrors often look greenish, revealing that they are not perfect mirrors but absorb different wavelengths a bit differently.
 

Similar threads

Undergrad Fabry-Perot Interferometer mirrors
  • · Replies 7 ·
Replies
7
Views
5K
Undergrad Do my parabolic mirrors need to be really shiny to reflect infrared?
  • · Replies 3 ·
Replies
3
Views
2K
High School Can a magnifying mirror or prism be used somehow as a low-tech reading aid for the visually impaired?
  • · Replies 11 ·
Replies
11
Views
2K
Undergrad Understanding magnification of concave mirrors for near-eye situation?
  • · Replies 11 ·
Replies
11
Views
3K
Undergrad Image construction with concave and convex mirrors
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Are these explanations for color/light-absorption correct?
  • · Replies 5 ·
Replies
5
Views
2K
High School Light beams and their reflection
  • · Replies 64 ·
3
Replies
64
Views
5K
Undergrad Optics question: Looking at mirrors from parallel to the surface
  • · Replies 6 ·
Replies
6
Views
2K
High School How would light work on a mirror very far away?
  • · Replies 11 ·
Replies
11
Views
2K
Undergrad How Can I Create a Mirror Reflection Illusion?
  • · Replies 5 ·
Replies
5
Views
2K