How does a cellular phone work?

Cellular, or cell, phones first became available to consumers in the early 1980s, but the technology that made them small and truly portable evolved gradually over the next 10 years or so. By the beginning of the twenty-first century, millions and millions of people in countries all over the world were using cell phones on a daily basis. And it isn’t just adults who enjoy the benefits of completely mobile phone capabilities: in the United States alone, more than 20 percent of teenagers have a cell phone. That translates to at least one in five American teens. The cellular system divides each city into many small cells (a large city can have hundreds). Each cell has its own tower (which contains an antenna as well as transmitters and receivers that send and receive signals). Each tower can handle numerous callers at a given time, and their small size and weaker signal (compared to the radio antennae) means that their signals don’t interfere with those of nearby towers. When you call someone using a cellular phone, your phone is sending and receiving signals via radio waves, invisible bands of energy that work like light rays. In other words, your cell phone is a fancy, high-tech radio. After you dial a friend’s number, your phone must find the closest tower by searching for the strongest signal. Once that signal is located, your phone transmits certain information—like your cell phone number and serial number—that help your service provider make sure you are one of their customers.

Then the mobile telephone switching office (MTSO) finds an available channel where your conversation can take place. The MTSO then completes the connection (all of this happening in a few short seconds) and you are chatting with your friend, without wires or cords to hold you down. If you are sitting in the back seat of the car while talking, and your mom is driving you from one end of town to the other, your call will be switched automatically from one cell tower to the next without any pause in your conversation.

What is paper made of?

Around the world, people have made paper from a wide variety of plant materials, such as wood pulp, rice, water plants, bamboo, cotton, and linen clothing. The ancient Egyptians made paper from papyrus reeds that grew abundantly along the Nile River. Today’s paper fiber comes mainly from two sources: pulpwood logs and recycled paper products. In fact, much of the paper today is a blend of new and recycled fiber. To make paper commercially, companies mash up these wood fibers and mix them with water.

This mixture is mashed into a thin sheet. The sheet is dried and pressed flat into large rolls, cut into different sizes, and converted into paper products. Recycling paper and paper products helps save trees and support the paper-making process. According to the American Forest and Paper Association more than half—53.4 percent—of the paper used in the United States was recovered for recycling in 2006.

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Can my cat or dog benefit my health?

As a matter of fact, yes! Researchers believe that regular contact with pets can reduce levels of stress and reduce blood pressure (the force of blood pushing against the walls of the arteries as the heart pumps out blood).

Pets offer stability, comfort, security, affection, and intimacy. Owning a dog also provides a great opportunity to get exercise and fresh air, since it will need to go for a walk every day.

Which was the biggest dinosaur?

Information about dinosaurs changes all the time as new bones are found and new evidence about their surroundings becomes available. The largest complete dinosaur fossil found by paleontologists (scientists that study dinosaurs) was Brachiosaurus (meaning “arm lizard”), a huge dinosaur that lived during the Jurassic Period. It weighed about 80 tons (72,640 kilograms) and reached 75.5 feet (23 meters) in length and 39 feet (12 meters) in height—about the length of two large school buses and the height of a four-story building. Parts of leg bones and vertebrae of even larger dinosaur species have been discovered, and scientists have studied these parts to try and determine their exact size.

Several of these—such as Argentinosaurus and Amphicoelias—might have been one and a half to two times larger than Brachiosaurus. The Argentinosaurus, thought to weigh as much as 100 tons (90,800 kilograms), was uncovered in the late 1990s in Argentina, which was home to many of the world’s largest dinosaurs. These gentle giants were once thought to live in watery, swampy regions, but recent evidence suggests that most of them were forest dwellers that ate leaves from the tops of trees. They had enormous bodies, very long necks, relatively small heads, and thick, tree-trunk-like legs, much like an elephant’s legs. They moved very slowly and did not have many ways to defend themselves, but their tremendous size kept most predators away.

How hot is the Sun?

The Sun is extremely hot. The surface of the Sun (or its outer visible layer, called the photosphere) is about 10,000 degrees Fahrenheit (5,537 degrees Celsius)— about 50 times the temperature required to boil water.

The core of the Sun, where solar energy is created, reaches 27 million degrees Fahrenheit (15 million degrees Celsius). It is so intense that nuclear reactions take place there.

Interesting facts about Psychology

1.    80% of women use silence to express pain. You know she’s truly hurt when she chooses to ignore you.
2.    Psychology says, friendship is not about who you spend the most time with, it’s about who you have the best time with.
3.    Psychology says, ironically, the more you hide your feelings, the more they show. The more you deny them, the more they grow.
4.    Being sarcastic on a regular basis can add up to 3 yrs to your life. Sarcasm is extremely healthy for the mind.
5.    Being able to respond with sarcasm to a stupid question within seconds is literally a sign of a healthy brain.
6.    Bad relationships change good people.
7.    Psychology suggest that sometimes you love someone so much that not even the truth can change your mind.
8.    The loneliest people are the kindest. The saddest people smile the brightest. The most damaged people are the wisest.
9.    Late night phone and text conversations tend to be the best.
10.    Work hard in silence, let your success be your noise.
11.    Psychology says, the person you care about the most can literally shatter your confidence with their opinions.
12.    Psychology says: People tend to value memories more than actual people. Sometimes you miss the memories, not the actual person.

13.    When it’s after 2am, just go to sleep. The decisions you make after 2am are always the wrong decisions.
14.    Psychology says, your personality is who you are. Your attitude is usually based on how a person treats you.
15.    70% of people pretend to be okay simply because they don’t want to annoy others with their problems.
16.    Positive events, such as graduating, getting married and a new job often lead to depression.
17.    Psychology says, the lyrics in your favorite song express everything that you struggle to say or express to others.
18.    Being in a relationship is not about kissing, dates or showing off. It’s about being with the person who makes you happy.
19.    People who laugh more are better able to tolerate pain – Both physical and emotional.
20.    Women are automatically more attracted to guys who make an effort to start the conversation, showing initiative and consistency.
21.    Psychology claims that If two past lovers can remain just friends, its either they are still in love, or never were.
22.    Generally, people are more likely to assume you’re being rude when you’re actually being honest.
23.    Your age doesn’t define your maturity, your grades don’t define your intellect, and rumors don’t define who you are.
24.    90% of people will fake laugh when they don’t understand what someone said to them.
25.    Psychology says, staying quiet doesn’t mean you’ve got nothing to say. It means you don’t think they’re ready to hear your thoughts.

How does the metal switch in a toaster bend?

It bends because it is made of two metals that are joined together, something called a bimetal switch. One metal (usually brass) expands quickly when heated, while the other expands much more slowly. This difference causes the switch to bend toward the low-expansion metal.

Bimetal switches are used in other appliances that switch electricity on and off to keep their temperatures even, like irons and refrigerators. The thermostat that regulates the temperature of your home by turning your furnace and air conditioner on and off also uses a bimetal switch.

Why do dogs bark?

Dogs bark to communicate with other dogs and with humans. Dogs are descendants of wolves, which are social animals that live in packs, and they share many of the behaviors that define the complex relationships that exist within such animal groups. Few domestic dogs live together in packs (though they often consider their human family their group), but they still use complicated behaviors that involve smell, sight, and hearing to communicate. A dog has many scent-producing glands that it uses to communicate. The scent that a dog leaves behind (in its urine, feces, and paw prints) can reveal its sex, age, and even its mood to other dogs that come sniffing by.

A dog uses its posture, facial expression, and ear and tail position to communicate with other dogs, too. And it uses its voice to communicate by whining, growling, howling, or barking. A dog usually whines or whimpers when it is in distress: when it is hungry, cold, or in pain. Growls indicate that a dog is angry and ready to fight. Barks usually show excitement.

Which muscles are the largest, and which ones are the smallest?

The largest muscle is the buttock muscle (gluteus maximus), which moves the thighbone away from the body and straightens out the hip joint. It is also one of the stronger muscles in the body. The smallest muscle is the stapedius, in the middle ear.

It is thinner than a thread and 0.05 inches (0.127 centimeters) in length. It activates the stirrup that sends vibrations from the eardrum to the inner ear. The longest muscle is the sartorius, which runs from the waist to the knee. Its purpose is to flex the hip and knee.

What happens during an eclipse of the Sun?

Once in a while the Moon passes directly in front of the Sun as it makes its way around Earth. It temporarily blocks out the Sun, casting a shadow on a portion of Earth that is experiencing day.

When this total eclipse of the Sun—a solar eclipse occurs, the part of Earth affected becomes dark and cold until the Moon passes by. Surrounding areas experience a partial eclipse, when just part of the Sun is temporarily covered by the Moon.