Today I Learn

25 March 2025 04:51

What percentage of the earth's water is frozen?

Of the three percent of the water that is not in the ocean, about 69 percent is locked up in glaciers and icecaps. Ninety percent of that frozen water is in Antarctica and about nine percent covers Greenland. Of the remaining freshwater, 30 percent of it is groundwater, captured below our feet.

Today I Learn

22 March 2025 05:38

​​Why Surgical Lamps don’t cast shadows?

Surgery lamps, also known as surgical lights or operating lights, are designed to provide high-intensity, focused lighting for surgeons during medical procedures.

One of the key features of these lamps is that they are designed to minimize shadows.There are several reasons why surgery lamps are able to reduce or eliminate shadows,

Multiple light sources: Surgery lamps often have multiple light sources, typically in the form of LEDs or halogen bulbs, that are arranged in a specific pattern. This allows the light to come from multiple angles, reducing the likelihood of shadows.

Diffusion: Some surgery lamps use a diffuser, which is a translucent or semi-transparent material that scatters the light in different directions. This helps to soften the light and reduce shadows.

Polarization: Some surgery lamps use polarized light, which can help to reduce glare and shadows. Polarized light is filtered to only allow light waves of a certain orientation to pass through, which can help to reduce reflections and shadows.

Beam shaping: Surgery lamps often have a beam-shaping system that allows the light to be focused and directed precisely where it is needed. This can help to reduce shadows by ensuring that the light is only illuminating the area of interest.

Shadow-reducing optics: Some surgery lamps use specialized optics, such as aspheric lenses or Fresnel lenses, that are designed to reduce shadows.

These optics can help to bend and shape the light in ways that minimize shadows.
Overall, the combination of multiple light sources, diffusion, polarization, beam shaping, and shadow-reducing optics all work together to help minimize shadows in surgery lamps.

Today I Learn

20 March 2025 03:29

Can a shark blink with both eyes?

Sharks have eyelids, but they do not blink because the surrounding water cleans their eyes. To protect their eyes some species have nictitating membranes. This membrane covers the eyes while hunting and when the shark is being attacked.

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Today I Learn

13 March 2025 03:04

Why is a dog's nose wet?

Wet Nose, Cool Body. Moist noses are also one of the ways that canines can regulate body temperature and cool down. “Dogs don't have normal sweat glands, like people,” says Dr. King, “so they secrete sweat from the pads of their feet and their noses.”

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Today I Learn

03 March 2025 06:26

When is the next time the planets will align?

One calculation of alignments within around thirty degrees (about as close as they can get) shows that the last such alignment was in 561 BC, and the next will be in 2854. All nine planets are somewhat aligned every 500 years, and are grouped within 30 degrees every 1 to 3 alignments.

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Today I Learn

28 February 2025 03:52

​​Why Surgical Lamps don’t cast shadows?

Surgery lamps, also known as surgical lights or operating lights, are designed to provide high-intensity, focused lighting for surgeons during medical procedures.

One of the key features of these lamps is that they are designed to minimize shadows.There are several reasons why surgery lamps are able to reduce or eliminate shadows,

Multiple light sources: Surgery lamps often have multiple light sources, typically in the form of LEDs or halogen bulbs, that are arranged in a specific pattern. This allows the light to come from multiple angles, reducing the likelihood of shadows.

Diffusion: Some surgery lamps use a diffuser, which is a translucent or semi-transparent material that scatters the light in different directions. This helps to soften the light and reduce shadows.

Polarization: Some surgery lamps use polarized light, which can help to reduce glare and shadows. Polarized light is filtered to only allow light waves of a certain orientation to pass through, which can help to reduce reflections and shadows.

Beam shaping: Surgery lamps often have a beam-shaping system that allows the light to be focused and directed precisely where it is needed. This can help to reduce shadows by ensuring that the light is only illuminating the area of interest.

Shadow-reducing optics: Some surgery lamps use specialized optics, such as aspheric lenses or Fresnel lenses, that are designed to reduce shadows.

These optics can help to bend and shape the light in ways that minimize shadows.
Overall, the combination of multiple light sources, diffusion, polarization, beam shaping, and shadow-reducing optics all work together to help minimize shadows in surgery lamps.

Today I Learn

17 February 2025 02:48

​​Why Surgical Lamps don’t cast shadows?

Surgery lamps, also known as surgical lights or operating lights, are designed to provide high-intensity, focused lighting for surgeons during medical procedures.

One of the key features of these lamps is that they are designed to minimize shadows.There are several reasons why surgery lamps are able to reduce or eliminate shadows,

Multiple light sources: Surgery lamps often have multiple light sources, typically in the form of LEDs or halogen bulbs, that are arranged in a specific pattern. This allows the light to come from multiple angles, reducing the likelihood of shadows.

Diffusion: Some surgery lamps use a diffuser, which is a translucent or semi-transparent material that scatters the light in different directions. This helps to soften the light and reduce shadows.

Polarization: Some surgery lamps use polarized light, which can help to reduce glare and shadows. Polarized light is filtered to only allow light waves of a certain orientation to pass through, which can help to reduce reflections and shadows.

Beam shaping: Surgery lamps often have a beam-shaping system that allows the light to be focused and directed precisely where it is needed. This can help to reduce shadows by ensuring that the light is only illuminating the area of interest.

Shadow-reducing optics: Some surgery lamps use specialized optics, such as aspheric lenses or Fresnel lenses, that are designed to reduce shadows.

These optics can help to bend and shape the light in ways that minimize shadows.
Overall, the combination of multiple light sources, diffusion, polarization, beam shaping, and shadow-reducing optics all work together to help minimize shadows in surgery lamps.

Today I Learn

12 February 2025 03:36

What is the difference between cold-blooded and warm-blooded?

​​The main difference between warm-blooded (endothermic) and cold-blooded (ectothermic) animals lies in their ability to regulate body temperature:

Warm-blooded (Endothermic) Animals:

-Maintain constant body temperature: Regardless of environmental temperature.
-Generate heat internally: Through metabolic processes, like cellular respiration.
-Sweat to cool down: To regulate temperature when it gets too high.

Examples: Mammals (humans, dogs, bears), birds, and some fish (like sharks).

Cold-blooded (Ectothermic) Animals:

-Body temperature varies with environment: They absorb heat from their surroundings.
-Rely on external heat sources: Like sunlight, water, or air temperature.
-Bask to warm up: Expose themselves to heat sources to increase body temperature.

Examples: Reptiles (snakes, lizards, turtles), amphibians (frogs, toads), fish (most species), and insects.

Key differences:

- Thermoregulation: Warm-blooded animals control their temperature internally, while cold-blooded animals rely on external sources.
- Metabolism: Warm-blooded animals have a faster metabolism to generate heat, while cold-blooded animals have a slower metabolism.
- Activity levels: Warm-blooded animals can maintain activity levels regardless of temperature, while cold-blooded animals are often more active in warmer temperatures.

Today I Learn

08 February 2025 02:49

​​​​What is Cabin Pressure and Why do we need to maintain it in Aeroplane?

Earth's atmospheric pressure varies with altitude. At the Earth's surface(sea level) , It is measured at 14.7 pounds per square inch(P.S.I) - which human beings are accustomed to because it provides the optimum amount of Oxygen.
As Aeroplane ascends to higher altitudes, the atmospheric pressure decreases. There isn't oxygen to breathe and humans cannot survive more than a minute at such altitudes.In order to prevent this from happening , Cabin Pressure is maintained at appropriate levels.
To maintain the pressure in the cabin equal to that at low altitude, even while the airplane is at 30,000 feet, the incoming air is held within the cabin by opening and closing an outflow valve, which releases the incoming air at a rate regulated by pressure sensors. Think of a pressurized cabin as a balloon that has a leak but is being inflated continuously.

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Today I Learn

03 February 2025 04:50

How many Sudoku puzzles are there?

There are a total of 6,670,903,752,021,072,936,960 possible solutions, yet when mathematicians took away rotations, reflections, permutations and relabeling, which takes away the same puzzle in just a different form, the number of solutions was 5,472,730,538.

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Today I Learn

23 January 2025 02:49

​​What is Narco Test?

A person is able to lie by using his imagination. In the Narco Analysis Test, the subject's imagination is neutralised by making him semi-conscious. In this state, it becomes difficult for him to lie and his answers would be restricted to facts he is already aware of.

Experts inject the subject with Sodium Pentothal or Sodium Amytal. The dose is dependent on the person's sex, age, health and physical condition.

A wrong dose can result in a person going into a coma, or even death.

The subject is not in a position to speak up on his own but can answer specific but simple questions.

The answers are believed to be spontaneous as a semi-conscious person is unable to manipulate the answers.

Sodium pentothal, or sodium thiopental, is a fast-acting, short-duration anaesthetic used in larger doses to sedate patients during surgery.

It belongs to the barbiturate class of drugs that act on the central nervous system as depressants.

Because the drug is believed to weaken the subject’s resolve to lie, it is sometimes referred to as a “truth serum” and is said to have been used by intelligence operatives during
World War II.

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Today I Learn

20 January 2025 07:53

Do snails have eyes?

Land snails have two sets of tentacles that stick out, the longer set of tentacles are the ones that have the snail's eyes. This way they can move their tentacles around to get the best view. Water snails, on the other hand, have eyes at the tentacles' base and they have only one pair of tentacles.

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Today I Learn

18 January 2025 05:22

​​What’s the Difference Between Copyright and Copyleft?

Intellectual property is a valuable asset for your business and it’s important that you take the necessary steps to secure its protection. One type of intellectual property that a business can own is copyright. This gives the owner an exclusive right of the copyright material to reproduce, reuse and republish it. However, there is a school of thought that seeks to override copyright and allow anyone to modify specific pieces of work. This form of licensing is known as copyleft and is commonly used in relation to software development. 

Copyright- Copyright attaches automatically to original artistic works. Therefore, you don’t need to register the right. When an author or creator expresses the idea in material form, the work gains copyright protection. Accordingly, you don’t have to publish material work for it to be afforded protection under copyright law.

Copyleft- Copyleft, as the name suggests, heads in the opposite direction to copyright. Playing on the word ‘copyright’, copyleft overrides copyright and promotes the concept that materials should be:
freely used, copied and modified by others.
Copyleft also requires that all versions of the material that users modify are freely accessible so that others can use and modify it. 
The principles of copyleft are commonly used within the software industry, where source code is often free for anyone to modify.

Today I Learn

09 January 2025 04:40

Why is there no wind on the equator?

The trade winds coming from the south and the north meet near the equator. These converging trade winds produce general upward winds as they are heated, so there are no steady surface winds. This area of calm is called the doldrums.

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Today I Learn

04 January 2025 04:14

Why do we blush when we are embarrassed?

Asap SCIENCE explains blushing as a reaction of the sympathetic nervous system and part of our “fight or flight” response. When you're embarrassed, adrenaline is released, speeding up your heart rate and dilating your blood vessels to improve your blood flow and oxygen delivery.

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Today I Learn

24 March 2025 04:36

This illusion is called "Mephisto spiral"

Today I Learn

21 March 2025 08:58

What countries border the Black Sea?

The Black Sea is an inland sea located between far-southeastern Europe and the far-western edges of the continent of Asia and the country of Turkey. It's bordered by Turkey, and by the countries of Bulgaria, Romania, Ukraine, Russia and Georgia.

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Today I Learn

14 March 2025 01:48

What is the temperature of dry ice?

Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid.

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Today I Learn

10 March 2025 02:31

Can animals see colors?

To see in full colour as we know it, humans use three cones – red, blue and green. However cats and dogs only have blue and green cones. This means they have a much more muted perception of colour, which is akin to colour blindness in humans.

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Today I Learn

03 March 2025 06:25

350 Million Year Old Water Trapped Inside A Amethyst Crystal.

Today I Learn

26 February 2025 07:07

Do bananas have seeds in them?

Wild bananas, prior to domestication, do have seeds. But like seedless grapes, humans have found and cultivated seedless mutations. So now all banana trees come from cuttings and there are no seeds in the fruit. The little brown specs in a banana are the vestiges of seeds that did not develop because of the mutation.

Today I Learn

15 February 2025 05:08

​​Why are Printed Circuit Boards usually green in colour?

A ‘green’ printed circuit board is not actually green all the way through. The only green part is the outer covering of resin called the solder mask or solder resist/oil. This is a hardened resin with colored pigments that is applied to the boards in a silkscreen fashion. The purpose of solder mask is to protect the electronic traces underneath from moisture and dust and to control the flow of molten solder. The actual core of a typical FR-4 circuit board is a plain, dull, yellow color, but the solder mask can come in many colors such as blue, red, yellow, black and white. Even more exotic colors can be found for the extravagant such as orange, pink, purple, matte versions and even mixed color boards. So, the question remains, why green?
Green can relieve visual fatigue and aid in inspections.

Other colors may not provide sufficient contrast for component visibility.
Some colors can interfere with automated optical inspection (AOI) systems.
- High-frequency or high-power PCBs might use different colors (e.g., red or blue) for better thermal dissipation.
- Specialty PCBs, like those for medical or aerospace applications, may use unique colors.

The green color has become an industry standard, but advancements in materials and designs may lead to more varied color options.

Today I Learn

09 February 2025 03:56

How fast was the meteor that killed the dinosaurs?

Scientists calculate that it was blasted into Earth by a 10-kilometer-wide asteroid or comet traveling 30 kilometers per second -- 150 times faster than a jet airliner. Scientists have concluded that the impact that created this crater occurred 65 million years ago.

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Today I Learn

05 February 2025 05:22

What height to reach terminal velocity?

A falling person will reach terminal velocity after about 12 seconds, falling some 450 m (about 1,500 ft) in that time. That person will not then fall any faster, so it makes no difference what distance they fall if it is more than 1,500 ft - they will still reach the ground at the same speed.

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Today I Learn

29 January 2025 01:58

What gas is released when you crack your knuckles?

The fluid contains the gases oxygen, nitrogen, and carbon dioxide. When you pop or crack a joint, you stretch the joint capsule. Gas is rapidly released, which forms bubbles. In order to crack the same knuckle again, you have to wait until the gases return to the synovial fluid.

Today I Learn

22 January 2025 04:39

How long is human gestation from conception?

The average length of human gestation is 280 days, or 40 weeks, from the first day of the woman's last menstrual period. The medical term for the due date is estimated date of confinement (EDC). However, only about four per cent of women actually give birth on their EDC

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Today I Learn

19 January 2025 04:02

​​What is Narco Test?

A person is able to lie by using his imagination. In the Narco Analysis Test, the subject's imagination is neutralised by making him semi-conscious. In this state, it becomes difficult for him to lie and his answers would be restricted to facts he is already aware of.
Experts inject the subject with Sodium Pentothal or Sodium Amytal. The dose is dependent on the person's sex, age, health and physical condition. A wrong dose can result in a person going into a coma, or even death.
The subject is not in a position to speak up on his own but can answer specific but simple questions. The answers are believed to be spontaneous as a semi-conscious person is unable to manipulate the answers.
Sodium pentothal, or sodium thiopental, is a fast-acting, short-duration anaesthetic used in larger doses to sedate patients during surgery.
It belongs to the barbiturate class of drugs that act on the central nervous system as depressants.
Because the drug is believed to weaken the subject’s resolve to lie, it is sometimes referred to as a “truth serum” and is said to have been used by intelligence operatives during
World War II.

Today I Learn

13 January 2025 02:21

Do snails have eyes?

Land snails have two sets of tentacles that stick out, the longer set of tentacles are the ones that have the snail's eyes. This way they can move their tentacles around to get the best view. Water snails, on the other hand, have eyes at the tentacles' base and they have only one pair of tentacles.

@TodayILearn

Today I Learn

07 January 2025 02:28

​​Why so some lifters pass out from Heavy Deadlifts?

Weightlifting is an anaerobic exercise.
The reason lifters pass out is due to a phenomenon called orthostatic intolerance: the body's inability to quickly vasoconstrict when blood pressure drops suddenly.

When lifters pick up heavy weights, their blood pressure soars and their blood vessels dilate.
Lifters experience a drop in blood pressure when they drop the weight, because their blood vessels remain dilated despite the weight being removed.

The blood pressure can drop so much that the brain is starved for a split second, triggering a syncopal response.
The body's response to this sudden drop in blood pressure is syncope, causing lifters to faint and fall horizontally, which enables blood to reach the brain once again.

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Today I Learn

03 January 2025 03:09

Can it snow when it's below freezing?

It rarely snows when the temperature drops below zero degrees Fahrenheit (-18 degrees Celsius). But snow does sometimes fall even when it's that cold. Snow can fall even in the coldest place on Earth, Antarctica, at temperatures well below zero. It turns out that moisture is more important than temperature.

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