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WHY is everything colored green in night vision devices?
In traditional night vision devices (not thermal imagers), light entering the lens is converted into shades of black and white, and only when it hits the phosphor screen does it take on a greenish hue.
The green gamut is chosen for two reasons:
✔ the human eye is most susceptible to waves of this length.
✔ it is the least tiring to the eye for prolonged exposure.
In traditional night vision devices (not thermal imagers), light entering the lens is converted into shades of black and white, and only when it hits the phosphor screen does it take on a greenish hue.
The green gamut is chosen for two reasons:
✔ the human eye is most susceptible to waves of this length.
✔ it is the least tiring to the eye for prolonged exposure.
WHY are the ribs of coins notched?
Coins used to be valued according to the amount of metal they contained. Fraudsters used to cut the metal off the edges, pocketing the gold and silver. It was incredibly difficult to catch them.
A solution to this problem was suggested by Isaac Newton, who was an employee of the British Royal Mint. He suggested making fine notches on the edges of the coin, which made the worn edges immediately visible.
Coins used to be valued according to the amount of metal they contained. Fraudsters used to cut the metal off the edges, pocketing the gold and silver. It was incredibly difficult to catch them.
A solution to this problem was suggested by Isaac Newton, who was an employee of the British Royal Mint. He suggested making fine notches on the edges of the coin, which made the worn edges immediately visible.
WHY do babies have 70 more bones than adults?
Newborns tend to have about 270 bones, most of which are tiny. This makes the skeleton more flexible and helps the baby get through the birth canal and grow quickly. As they get older, many of these bones fuse together.
📌The adult skeleton consists of an average of 200-213 bones.
Newborns tend to have about 270 bones, most of which are tiny. This makes the skeleton more flexible and helps the baby get through the birth canal and grow quickly. As they get older, many of these bones fuse together.
📌The adult skeleton consists of an average of 200-213 bones.
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WHY do girls blink twice as often as guys?
📌 And it's true, there is a long-standing proven fact by scientists that women blink twice as often.
It is based on the fact that women's nervous system is more impulsive than men's, it also affects blinking.
A long look at the opponent is a proof of dominance, while frequent blinking is vice versa. In addition, emotional details play an important role.
📌 And it's true, there is a long-standing proven fact by scientists that women blink twice as often.
It is based on the fact that women's nervous system is more impulsive than men's, it also affects blinking.
A long look at the opponent is a proof of dominance, while frequent blinking is vice versa. In addition, emotional details play an important role.
WHY do we drink tequila with salt and lemon?
Before drinking tequila, one should lick the salt, then drink the liquor and snack on a slice of lime.
No other liquor is drunk in this way❗
The reason for this ritual is that the salt and lime change the distinctive taste and smell of tequila and emphasize its original flavor.
Before drinking tequila, one should lick the salt, then drink the liquor and snack on a slice of lime.
No other liquor is drunk in this way❗
The reason for this ritual is that the salt and lime change the distinctive taste and smell of tequila and emphasize its original flavor.
WHY are clouds white at night?
A cloud is a collection of water droplets and ice crystals with no color and only partially diffuse light hitting them.
At night, low clouds appear whiter than the sky when the city lights are high.
In contrast, in a dark area, clouds obscure the faint glow of the night sky and appear black.
A cloud is a collection of water droplets and ice crystals with no color and only partially diffuse light hitting them.
At night, low clouds appear whiter than the sky when the city lights are high.
In contrast, in a dark area, clouds obscure the faint glow of the night sky and appear black.
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WHY do men and women hear sounds differently?
Women hear high pitched sounds better than men.
They are also better at recognizing changes in tone than men and therefore know exactly when men are lying😏
Men, on the other hand, specialize in wildlife sounds and hear perfectly well where the sound is coming from. If a woman is the first to hear a kitten's meow, it is the man who will indicate where to look for it.
Women hear high pitched sounds better than men.
They are also better at recognizing changes in tone than men and therefore know exactly when men are lying😏
Men, on the other hand, specialize in wildlife sounds and hear perfectly well where the sound is coming from. If a woman is the first to hear a kitten's meow, it is the man who will indicate where to look for it.
WHY is soap easier to wash off with warm water?
In warm water, molecules are more mobile and more active in interacting with soap molecules, pulling them off the skin and converting into water-suspended droplets.
In this form, detergents are easily removed from the surface along with pollutants inside these "droplets".
In warm water, molecules are more mobile and more active in interacting with soap molecules, pulling them off the skin and converting into water-suspended droplets.
In this form, detergents are easily removed from the surface along with pollutants inside these "droplets".
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WHY do human eyes move in sync?
The coordinated movement of the eyes allows us to build a three-dimensional image of an object and accurately estimate the distance to it.
➡️ But some sedentary animals (chameleons, seahorses) have eyes that can move independently of one another.
The coordinated movement of the eyes allows us to build a three-dimensional image of an object and accurately estimate the distance to it.
➡️ But some sedentary animals (chameleons, seahorses) have eyes that can move independently of one another.
WHY is a dog's nose wet and cold?
Interestingly, in this condition, the dog can smell better. In dogs, mucus covers not only the inside, but also the outside of the sense of smell. This secret is produced by glands in the lining of the nose and serves as a sort of filter through which the animal analyzes smells.
Its moist nose allows it to detect even the slightest fluctuations in the air and their direction. It also has a keen sense of smell that allows it to not only pick up odors, but also to separate them from each other.
Interestingly, in this condition, the dog can smell better. In dogs, mucus covers not only the inside, but also the outside of the sense of smell. This secret is produced by glands in the lining of the nose and serves as a sort of filter through which the animal analyzes smells.
Its moist nose allows it to detect even the slightest fluctuations in the air and their direction. It also has a keen sense of smell that allows it to not only pick up odors, but also to separate them from each other.
WHY doesn't food burn in oil?
When frying in a pan without oil, the food only gets hot at the bottom and the top is not heated, being completely soggy. The oil gives off heat from the lower layers to the upper ones.
The boiling point of oil gives the crust on the food, but you can't get it with cooking, water interferes in the process, it adjusts to its boiling point, which is lower than that of oil.
When frying in a pan without oil, the food only gets hot at the bottom and the top is not heated, being completely soggy. The oil gives off heat from the lower layers to the upper ones.
The boiling point of oil gives the crust on the food, but you can't get it with cooking, water interferes in the process, it adjusts to its boiling point, which is lower than that of oil.
WHY is business class located in the front of the plane if it's safer in the back?
The probability of surviving a crash in the back of a plane is not much higher than in the front seats, only a few percent. Considering that plane crashes are rare (once per million flights), this difference can be neglected.
More important are the advantages of the front seat: quick landing and disembarkation, lower noise level and the view from the porthole, which is not obscured by the wing and the engines.
The probability of surviving a crash in the back of a plane is not much higher than in the front seats, only a few percent. Considering that plane crashes are rare (once per million flights), this difference can be neglected.
More important are the advantages of the front seat: quick landing and disembarkation, lower noise level and the view from the porthole, which is not obscured by the wing and the engines.
WHY don't mice like cheese?
Contrary to popular myth, mice are not as big a fan of cheese as they are often portrayed in cartoons and even movies.
The basic diet of mice, like other rodents, consists of grains, seeds, pieces of vegetables, fruits and sweets. In addition, many cheeses have a pungent odor that is more likely to scare away a mouse.
Contrary to popular myth, mice are not as big a fan of cheese as they are often portrayed in cartoons and even movies.
The basic diet of mice, like other rodents, consists of grains, seeds, pieces of vegetables, fruits and sweets. In addition, many cheeses have a pungent odor that is more likely to scare away a mouse.
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WHY do cats purr?🐈
The sound and vibration are created by the muscles inside the cat's larynx.
When they move, the vocal cleft expands and contracts. The air vibrates every time the cat inhales and exhales.
What do we end up with? Purring.
The sound and vibration are created by the muscles inside the cat's larynx.
When they move, the vocal cleft expands and contracts. The air vibrates every time the cat inhales and exhales.
What do we end up with? Purring.
WHY does the skin on fingers get wrinkled in water?
Our distant ancestors used to extract from water bodies not only food, but also household items. No special equipment was available, so they had to do it with their bare hands.
Skin wrinkling on palms and fingers made the task a lot easier and changing the skin on feet simplified moving over underwater rocks and other slippery surfaces.
Our distant ancestors used to extract from water bodies not only food, but also household items. No special equipment was available, so they had to do it with their bare hands.
Skin wrinkling on palms and fingers made the task a lot easier and changing the skin on feet simplified moving over underwater rocks and other slippery surfaces.
WHY is limescale in the kettle not considered harmful to humans?
If a person swallows some scale, he or she will only get an unpleasant feeling in the mouth. Limescale is mainly calcium and magnesium salts, physiologically inactive due to their insolubility.
However, these layers do not conduct heat well: settling on the heater, they increase the boiling time of water and are harmful only to the kettle itself.
If a person swallows some scale, he or she will only get an unpleasant feeling in the mouth. Limescale is mainly calcium and magnesium salts, physiologically inactive due to their insolubility.
However, these layers do not conduct heat well: settling on the heater, they increase the boiling time of water and are harmful only to the kettle itself.
WHY does the Eiffel Tower grow 15 centimeters in summer?
It's all about temperature compensators. Thanks to them, steel can expand and contract without being damaged.
When steel heats up, it begins to stretch and occupy a larger volume. It is known as thermal expansion. Conversely, a drop in temperature leads to a decrease in volume.
It's all about temperature compensators. Thanks to them, steel can expand and contract without being damaged.
When steel heats up, it begins to stretch and occupy a larger volume. It is known as thermal expansion. Conversely, a drop in temperature leads to a decrease in volume.