Today I Learn

23 Jun 2025 04:16

What is the name of our planet's largest hot desert?


The Sahara desert in Africa is the largest desert in the world. In fact, Sahara is only the largest HOT desert as the Arctic desert and the Antarctic desert are bigger, but are usually referred to as polar deserts. 

Today I Learn

15 Jun 2025 05:42

Which color has the highest frequency?

Out of the 7 colours of the rainbow, violet has the highest frequency and the smallest wavelength.

Today I Learn

27 May 2025 07:21

What is the dew point?

Dew point temperature is defined as the temperature to which the air would have to cool (at constant pressure and constant water vapor content) in order to reach saturation. A state of saturation exists when the air is holding the maximum amount of water vapor possible at the existing temperature and pressure.

Today I Learn

18 May 2025 03:16

Why do we have two sets of teeth?

The reason you have two sets of teeth probably comes down to size. A full set of permanent teeth would be too big to fit into a young child's mouth. So milk teeth act as a bridge until the jaw is large enough to accommodate a full set of permanent teeth. The last teeth that emerge are your wisdom teeth.

Today I Learn

30 Apr 2025 06:16

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Today I Learn

24 Apr 2025 06:29

Can fish breathe out of water?

Though some fish can breathe on land taking oxygen from air, most of the fish, when taken out of water, suffocate and die. This is because gill arches of fish collapse, when taken out of water, leaving the blood vessels no longer exposed to oxygen in air.

Today I Learn

16 Apr 2025 04:27

Which is the only snake that builds a nest?

The female snake, about 13 feet long, builds a nest to lay its eggs. In fact, the King Cobra is the only snake in the world that builds a nest.

Today I Learn

05 Apr 2025 02:35

What does the Mohs scale measure?

A scale used to measure the relative hardness of a mineral by its resistance to scratching. From softest to hardest, the ten minerals of the Mohs scale are talc (measuring 1 on the scale), gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond (measuring 10 on the scale).

Today I Learn

24 Mar 2025 04:36

This illusion is called "Mephisto spiral"

Today I Learn

21 Mar 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.

@TodayILearn

Today I Learn

14 Mar 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.

@TodayILearn

Today I Learn

10 Mar 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.

@TodayILearn

Today I Learn

03 Mar 2025 06:25

350 Million Year Old Water Trapped Inside A Amethyst Crystal.

Today I Learn

26 Feb 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 Feb 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

17 Jun 2025 04:23

What are the highest and deepest point in the world?

Highest point Mount Everest (at approximately 8,850 meters) and Lowest point Mariana Trench ( at 11,034 meters deep below ocean).  If you placed Mount Everest at the bottom of the Mariana Trench, the peak would still be 2,133 meters below sea level.

Today I Learn

11 Jun 2025 02:45

What is the only vegetable that is never frozen?

The only vegetable or fruit never sold frozen, canned, processed, cooked, or in any form other than fresh is.... Lettuce.

Today I Learn

22 May 2025 03:31

Is White Light the absence of color?

In the visible spectrum, white reflects light and is a presence of all colors, but black absorbs light and is an absence of color. Black can be defined as the visual impression experienced when no visible light reaches the eye.

Today I Learn

07 May 2025 06:00

Where did hieroglyphics develop?

The hieroglyphic system used in ancient Egypt had between 700 and 800 basic symbols, called glyphs. This number grew in the last centuries of ancient Egyptian civilization, because of an increased interest in writing religious texts.

Today I Learn

26 Apr 2025 04:17

Do bears sleep all winter long?

It is a common misconception that bears hibernate during the winter. While bears tend to slow down during the winter, they are not true hibernators. Black bears, Grizzly bears and Brown bears do go into a deep sleep during the winter months, known as torpor. Hibernation is when animals “sleep” through the winter.

Today I Learn

19 Apr 2025 05:54

Which country has the most islands in the world?

The five main archipelagos are Indonesia, Japan, the Philippines, New Zealand, and the British Isles. The largest archipelagic state in the world, by area and population, is Indonesia. The archipelago with the most islands is the Archipelago Sea in Finland.

Today I Learn

12 Apr 2025 02:33

What color is between red and blue?

In between these colours may be seen secondary colours that are, perceptually, each a mixture of two of the primaries. Thus, you will see yellow between red and green, and cyan blue between green and blue-violet. The third secondary colour of light is magenta.

Today I Learn

25 Mar 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 Mar 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 Mar 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.

@TodayILearn

Today I Learn

13 Mar 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.”

@TodayILearn

Today I Learn

03 Mar 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.

@TodayILearn

Today I Learn

28 Feb 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 Feb 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 Feb 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.