Why do we see a red colour when we hold our palm against a light source ?
Why are fishes not able to survive in distilled water ?
What causes blue fingernails ?
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SCIENCE FACTS
SCIENCE FACTS
Why do we see a red colour when we hold our palm against a light source ?
In the visible spectrum , red has the highest wavelength , and lies in the range of 650- 750 nm . Its depth of penetration into human tissues is approximately around 3mm as seen from the graph below . This is much higher than the other wavelengths present in the visible spectrum . Since light at the edges of our fingers have to traverse a smaller distance , around 2mm to 5mm , we see red to be the prominent colour . This is referred to as Near- Infrared window ( NIW ) which defines the range of wavelengths where light has its maximum depth of penetration . This property has been utilized in numerous applications ranging from spectroscopic imaging to treatment of brain tumours .
Why are fishes not able to survive in distilled water ?
Take a fresh grape fruit and keep it in distilled water for an hour . It is stouter than before . Another fresh grape fruit kept in salty water for an hour will appear slim and wrinkled . The grape has dissolved minerals , sugars and other ingredients in its juice . The skin of the grape is a semi permeable membrane across which water can diffuse from one side to the other through osmosis . When the grape is kept inside distilled water , the concentration ( salinity ) of juice in the grape is higher than that of water and water moves osmotically from outside the grape to inside . Hence the grape appeared stouter . The reverse happened in the case of salty water .
The skin of the fish is like the skin of the grape fruit . If the fish is in distilled water , there is an osmotic flow of water from outside the fish to the inside because the salinity of the fish body is higher than that of water . Thus there is a danger of dilution of the body fluids of the fish or at worst that of being blown out if the fish is to be in distilled water for a very long period of time .
What causes blue fingernails ?
Blue fingernails are caused by a lack or low level of circulating oxygen in your red blood cells . This condition is known as cyanosis . It occurs when there isn ’ t enough oxygen in your blood and the skin or membrane below the skin
WINSPIRE : Empowering youth | February , 2017