Monday, May 27, 2013

Why are there no B batteries, while A, C and D exist?


In 1924,the ANSI - American National Standards Institute, USA, proposed a simple system to designate cell sizes, based on the letters of the alphabet, starting with the smallest cell in volume and going in ascending order, A, B, C, etc.
B batteries never really caught on commercially, at least on the consumer end of things.  B batteries were primarily used in devices that used vacuum tubes which is outdated technology. A size batteries are hard to find as well, because they were primarily used in really old laptop batteries.
The ones that were most popular just ended up being the AA, AAA, C, and D. Most batteries (AA, AAA, C, D) all carry the same voltage, 1.5 volts, but they differ in their capacities, their physical size.

Sunday, May 26, 2013

Are zebras white with black stripes or black with white stripes?


Zebras are native to central and southern Africa. They are black with white vertical stripes on the head, neck, forequarters, and main body, usually with horizontal stripes at the rear and on the legs of the animal.
Zebras are dark animals with white stripes where the pigmentation is inhibited. The pigment of the hair is found solely in the hair and not in the skin.

Wednesday, May 22, 2013

How far can the human eye see?



You see because the light reaches your retina. You can see as far as a light source can reach your retina with enough intensity  How far the human eye can see depends on how many particles of light, or photons, a distant object emits. Theoretically, there is no limit to the distance we can see, the object just has to be large enough or emitting enough radiation. So the human eye can see until its line-sight hits an obstacle. Healthy human sight can see an almost unlimited distance. Normally vision is stopped by something blocking it. If you are looking at the horizon the curve of the earth stops you from seeing farther. The farthest thing that a human can see without a telescope is the Andromeda Spiral galaxy, which is about 2 million lightyears away.

Friday, May 17, 2013

Why cant we drink sea-water?


Our bodies are mostly water (~75%). The water in our bodies supports many functions, including waste removal and temperature regulation. Since water is consumed and expelled by these functions, we need to constantly replenish our water reserves to survive. In normal circumstances, the saltiness of water in your cells is the same as the saltiness outside your cells. But when your cells consume water, the solution becomes more concentrated, and the natural process of osmosis allows water from outside your cells to pass into your cells to achieve equilibrium. That’s how we absorb water as per need.
The opposite happens when drinking sea (salt) water. The salinity outside your cells increases rapidly and water from cell moves out, causing the cells to dehydrate. A person may die of extreme dehydration.

Thursday, May 9, 2013

Why does Earth rotate from west to east?

The angular momentum of pretty much the whole solar system is in the west to east direction. All the planets, the sun rotate that way. Venus and Uranus are the exception, as they rotate differently.  According to astronomers the rotation and orbits of the planets and stars are largely determined by conservation of angular momentum.  The direction of the rotation largely relies on gravity and other conditions in play as each celestial body is formed and enters its orbit.

Tuesday, May 7, 2013

Why do we have two eyes but see only one image?


When viewing with two eyes, the muscles that control our eyes work automatically to focus both eyes on the same spot. Each eye receives light photons that are focused upon the retina by the lens to form an image. The 'image' is transmitted by the optical nerves of both eyes to layers of brain tissues at the back of the head. The brain then processes both the images to form single 3D image. Basically, if you close one eye, you can still see, but in a single plane. So even though your brain tries to add depth, what we see is a flat a flat image with one eye. But with two eyes next to each other, you can you can view the relative depth.

Because the eyes are a few inches apart the images are slightly different permitting depth perception. The left and right eyes balance the image’s depths and shadows. This is the reason why we see the image shapes. Both eyes together help to see the distance of the object.

Monday, May 6, 2013

Why does a smile make you happy?


Smiling usually happens without much thought. It is one of the most important nonverbal communication skills we possess.  Smiling just using the muscles in the face to turn your cheeks upward releases endorphins that aid in creating a positive mood. Sometimes your joy is the source of your smile, but sometimes your smile can be the source of your joy. Scientists have found compelling evidence that smiling causes people to feel happy, regardless of how they felt at first. Smiles are infectious. So even if you don’t feel much happier, the people around you are more likely to smile, and that can improve your mood as well. Smiling can reflect inner happiness, but it is also a great way to give happiness to others. One reason smiling faces trigger increased happiness is that the set of the facial muscles a smile produces is associated with happiness by the brain.
Human being is  social animal and our well-being often depends on our ability to gauge the emotions of those around us. Smiling is one major social cue. Smiling is a socially accepted feelings transmitter.