Have you ever wondered why some things become dark when you spill water on them? What’s exactly happening?
*********** Well, let’s find out. !
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Before I explain this phenomenon to you, let’s go through some prerequisite knowledge.
- How we see things
- (Types of reflection (**********************
How we see things
We see an object when light altern off it and then enters our eye. The eye then produces a nerve impulse and sends it off to the brain to be interpreted. Light acts as a medium of information transferhere.
This is why you can’t see things in dark; no light means that there is no way that you can channel the information about the surroundings into the person’s eye.
Types of reflection
Now let’s understand thenatural phenomenon of reflection; It’s when a wave hits a surface and gets thrown back. Notabsorbed(transfer it’s energy to the surface), ortransmitted(go through the surface).
There aretwo types of reflection(two ways the wave can be thrown back).
This is when all theincident light(light which hits the surface) is reflected into a single outgoing direction.
In this type of reflection, the angle at which light hits the surface is the same angle at which the light leaves the surface (reflected ). This type of reflection tends to happen on smooth surfaces like a mirror or glass.
Diffuse Reflection
This is when the incident light (light which hits the surface) is scattered into all angles when reflected. This is due to the irregular nature of the surface it’s reflected off.
The reflected light rays leave at a variety of angles. This is because the angle of incidence (the angle at which the light hits the surface) is different for each part of the surface.
Right, let’s say you accidentally spill water on your shirt. And now it’s dark. What’s precisely happening under the hood?
Once you spill water on the shirt, that part of the shirt is now covered with a thin film of water. So, any light which has to reflect off that part of the shirt has to go through water.
Before water is spilt, (******************************************************************% of the light traveling towards that part of the shirt will hit the surface. But now only a fraction of the light moving towards it will hit its surface. This is because the light now has a layer of water to go through. And due to thereflectanceof water, not all light at the
- air-liquid-interface
(border between air and water) goes through the water. Some of it is reflected.
The probability of light getting transmitted into the water is
Now, the incident light ray is inside the water. And it then hits the surface of the shirt. Some of the light is absorbed there, and the rest is reflected diffusely. How diffuse reflection occurs is explained above.
Due to the diffuse reflection, the light ray is scattered in many directions. All the light rays are now heading to the
- liquid-air interface
********* Let’s understand the phenomenon of Total internal reflection
is a natural phenomenon, where the incident light is reflected at media interface.
It only takes place if:
The current medium is denser than the medium it is going into.
Since water is denser than air, and the reflection is diffuse. A lot of light is internally reflected, thereof, increasing the probability of absorption at surface.
So this is it!
Everything in this essay comes from this source.
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