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Sharpen Your General Knowledge
Shamim Ansary:
What Are X-Rays and When Were X-Rays Discovered?
X-rays are electromagnetic radiation with short wavelengths, 10-3 nanometers, and a great amount of energy.
They were discovered in 1898 by William Conrad Roentgen (1845-1923).
X-rays are frequently used in medicine because they are able to pass through opaque, dense structures such as bone and form an image on a photographic plate.
X-rays are therefore commonly used to take images of the inside of objects in diagnostic radiography and crystallography.
Shamim Ansary:
What Is the Moon’s Landscape Like and What Other Features Does the Surface of the Moon Have Besides Craters?
The Moon’s surface has highlands and lowlands just like earth.
The main feature on the Moon’s surface are the hundreds of thousands of craters, or the remnants of craters, found in both regions, some with crater rays of ejected lunar material emanating out from their edges.
Besides craters, there are mountains, mares, rills, and domes.
The South Pole-Aitken basin is the largest, deepest and oldest basin recognized on the Moon.
At about 2,240 km in diameter, it is also the largest known crater in the Solar System.
Shamim Ansary:
Is Snow Frozen Rain?
Hail or sleet is frozen rain, but snow is never formed as a frozen raindrop.
Snow forms from ice crystals high above the earth. These particles turn into snow without first becoming rain.
At the height that snow usually forms, the temperature is from 20 to 60 degrees below zero, far too cold for water to exist as a liquid.
Shamim Ansary:
How Does Soap Get You Clean?
Have you often felt what a bother it was to use soap when a quick swish of your hands under plain water would do just as well? Most kids prefer it that way. But while water alone may remove some of the dirt from the surface of your skin, soap added to the water does get you cleaner.
If you looked at a cross-section of your skin under a microscope, you would see that it has many hollow areas, or valleys, where particles of grease and dirt can become embedded. Water alone may get under the dirt and push some of it out, but when that water hits grease, it will simply sit on top of it in a bubble or just roll off.
But add soap to that very same water and you have a completely different action. The action of mixing soap into water pumps air into the water and forces it to spread out as it creates bubbles. A bubble is actually a balloon of air with a thin outer covering of soap and water.
While bubbles seem to be very delicate and weak things, they actually work like dozens of strong magnets. Just as magnets pull tacks towards them, soap bubbles-pick up dirt and pull it away from the skin. Then the dirty bubbles are carried away in the rinse water, leaving your skin clean.
Shamim Ansary:
Why Are There More Female Babies Born Than Males?
In fact, each year more males are born than females. The normal slight excess of male births is usually attributed to the slightly greater motility of sperm carrying the male, or Y, chromosome.
It was recently discovered that in the average ejaculation, there are slightly more sperm carrying the X chromosome, necessary for conception of a female, than there are sperm with the Y chromosome. But emerging studies of embryos that have been conceived through in vitro fertilization indicate that more males are actually conceived.
Scientists suggest that the Y-bearing sperm are so much better at fertilizing eggs than the X-bearing ones that even though there are fewer of them to begin with, they end up penetrating more than half of all eggs.
What happens to the sex ratio after conception is another story. For example, in societies where women are not valued as much as men, they may be purposely aborted, neglected, or actually killed. In others, where men are subjected to greater stress or risk (from wars, for example), more women survive longer.
The ratio of males to females can vary from time to time and from population to population, whether it is animals or people, and there are numerous suggested reasons.
For example, it has been reported that women in lower socioeconomic groups, presumably under greater stress, bear slightly more girls than boys.
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