why do we need light to see
Does this seem like a strange question? It could be if you don't really think about it, but, could we survive without light? Food : Light is the sole source of food generation for all living organisms on the earth. Except for a few
almost all living beings depend on light for their food and energy. and other autotrophs synthesize their own food materials by use of light. The light converts to reserve energy in the form of food by a process known a photosynthesis. From these plants animals get the required food materials and the required. So plants depend on sunlight for their own food and animals depend on plants. Thus all the living beings are dependent on light for food. Answer 2: Great question! Its a complex topic but I will try my best. So, things that have color consist of different materials, which consist of different chemicals, which consist of different atoms.
All these elements are responsible for the properties of the surface of the thing that reflects light. The way the thing reflect light we see as color. Think of atoms like little bricks and chemicals like the way the wall is made from those bricks. So now you throw the ball into the wall. Depending of whether the wall is smooth or has sharp corners, or bended, or has big holes or has holes where the ball may stuck, your ball may jump back in different directions or just go through the wall, or be stuck in one of the tricky corners. Same with every surface when light hits it, surface may reflect the light back; it can absorb light or just let it go through (transparent things). So now, we need to talk more about light: we were talking about one ball hitting the wall, while light is more like a lot of balls of different size hitting the wall at the same time.
Because balls are of different size, some of them will be mostly bounded back, while others may be mostly stuck in the wall. Different objects (like lamps or sun or fire) emit energy (we imagine it as "balls" for now). Those balls are of different size. If you collect them from all over the universe and put all in the order from the very little to the very big you get what scientists call "spectrum" - the range of energy from ultraviolet to radio waves. Our sun emits energy of certain range (balls sizes are, lets say, only from 2 to 5 cm, not more, not less). So our eyes were developed to be sensitive only to those size of "balls" (others were not important as there were not many hitting our earth). so when sunlight hits the surface, for example the plant leave, the balls size 4 are mostly jumping back (while others are absorbed), and balls 4 reach our eyes.
Our eyes react to the "balls" of certain size as color. So ball size 4 we call "green", the balls size 2 we call blue etc. So now, the interesting conclusions: things do not have color by themselves. only when light (energy) hits them - we can see colors. You probably noticed that when it is dark, things get grayish and its hard to distinguish colors. Another interesting conclusion - our eyes are only sensitive to a little part of spectrum, or in other words can see only a little part of all possible colors. Thats why we develop instruments, like different spectrometers to learn about those "balls" we can not see with our eyes. And, finally, summing up the story: colors are out interpretation on the ability of things (surfaces) to reflect the certain part of light. And different things have different colors as their light reflecting properties are different.
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