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Course: Middle school physics > Unit 4
Lesson 4: Absorption and reflectionAbsorption and reflection
Review your understanding of absorption and reflection in this free article aligned to NGSS standards.
Key points:
- Reflection happens when a wave bounces off of a boundary between two materials.
- Reflection depends on the type of wave, the wave’s frequency, and the material.
- Absorption happens when a wave loses energy as it transmits into a material. This can happen in a medium or at a boundary between two materials.
- When a wave is absorbed by a material, its energy turns into another form of energy, such as thermal or electrical energy.
- The amount a wave is absorbed depends on the type of wave, the wave’s frequency, and the material.
Want to join the conversation?
- Question: What happens if the light hits right where the sand and water meet, what would happen then? Would the surface reflect, absorb or both? Correct me if I am being dumb.(37 votes)
- No, your question is not dumb. It's perfectly reasonable and means you were really thinking about the lesson :)
To answer you though:
No surface is completely reflective, so if you have a bowl of water in the sunlight some of the light hitting the surface will reflect but some of the light will still be absorbed.
At the point where the sand and water meet it will depend on how much they are mixed. If the sand is super saturated and there is much more water than sand, the boundary is minuscule therefore it will reflect. (but like I said, nothing is perfectly reflective so much more light will be absorbed in this scenario than of the bowl of just water)
Similarly, if there is more sand than water, the boundary is 'bigger'. So the light hitting it will be absorbed with little to no reflection.
I hope this helped. Just remember, boundaries are just the stopping point of reflection.
Stay inquisitive! :)(61 votes)
- Absorption happens when a wave loses energy as it transmits into a material. This can happen in a medium or at a boundary between two materials. what is the meaning of "boundary"?(6 votes)
- Consider a system made up of two media. Then the boundary in such a case would refer to the 'interface' where the wave leaves the first medium and enters the second medium as it travels.(18 votes)
- How does a hat reflect light? It's not even a shiny surface so how?(3 votes)
- Not only shiny things reflect light. Everything around us that we can see is reflecting light to some degree, that's why we could see it. Darker colours just reflect less light than lighter colours, and shiny/smooth surfaces (like a mirror or countertop) do not scatter light like a rougher surface might (like your hat). When light hits your hat, it still bounces off into your eye, but the reflected light is all going in different directions because of the rough material.
please someone fact check and confirm this-(12 votes)
- A wave needs a medium to go through, but light from the sun doesn't go through a medium (because space is blank), so how does it happen? I know the Michelson-Morley experiment was conducted to find the supposed medium called aether, but I still don't fully understand it. Could you please answer and explain?(6 votes)
- This is true for mechanical waves, but electromagnetical waves (like light) do not need a medium.(7 votes)
- Is there a material that could reflect all of the light that hits it?(7 votes)
- It would either have to be, like white beyond imagination, so like, vantablack(look it up) but white, or some kinda S U P E R M I R R O R. TBH I don't know the awnser, there may be something like that idk about. Great question though. I encourage you to do your research.(4 votes)
- Wait a sec so that means that since the light couldn't get to your eye it means that you cant see the reflected light it right? that would also mean that if the light could get to your eye you'd be able to see everything around you. someone help meee and vote me(6 votes)
- Actually the eye is reflected on because of our pupil or our retena(3 votes)
- so when the light hits the water it reflects back up but the ground absorbs it(5 votes)
- yes when water is still and you look at it does it reflect but if you look at the ground does it reflect?(4 votes)
- Wouldn't it lose energy when it is reflected(4 votes)
- Yes! Light loses energy as it is reflected. But it is in small amounts and also depends on the absorbency of the surface which it's being reflected off of.
:)(6 votes)
- Random Thought: We, culturally, think of green as the color of nature and clean products. However, since most flora (plants, leaves, seeds, etc.) reflects green, that means it is the only color of light that it doesn't absorb as energy through photosynthesis and therefore a mostly useless color to plants. Please prove me wrong.(6 votes)
- so basically the more opaque an object is, the more light it absorbs?(5 votes)
- Basically Yes(3 votes)