User:Melissa0813/sandbox

My contributions:

• Plants(Plant reproduction with out seeds)
• Animals (Crustaceans, Mammals)

• Waves

Mechanical waves and electromagnetic waves are two important ways that energy is transported in the world around us. Waves in water and sound waves in air are two examples of mechanical waves. Mechanical waves are caused by a disturbance or vibration in matter, whether solid, gas, liquid, or plasma. Matter that waves are traveling through is called a medium. Water waves are formed by vibrations in a liquid and sound waves are formed by vibrations in a gas (air). These mechanical waves travel through a medium by causing the molecules to bump into each other Sound waves cannot travel in the vacuum of space because there is no medium to transmit these mechanical waves.

• Light

Light is a member of the group of waves called electromagnetic waves. Others in the group are radio waves, infrared rays, x rays, and gamma rays. All of them are part of the electromagnetic spectrum. Elecromagnetic waves Electromagnetic waves, travel at a speed of 299,792 kilometers per second Wavelenght/Frequency Each electromagnetic wave has its own unique wavelength and frequency. A wavelength is the distance from one crest or trough to the next crest or trough. Frequency refers to the number of waves that pass by a given point n one second, or the number of vibrations per second. As wavelength or frequency increases, the other decreases. added animation of wavelenght Light When light strikes an object, the light either passes through the object, or it is reflected, or it is absorbed and converted into heat. Light travels at a speed of 300,000 kilometers per second. It takes 8 minutes to travel from the sun to earth. One Light year is at about 9.5 trillion kilometers. added images

• sound

Sound is produced when materials vibrate. Energy in sound waves can be transmitted from one substance to another. The air molecules are pressed together when the vibrating object moves forward and pushes against them. Compression, is when molecules are pressed together. Rarefaction, where molecules are spread out. And one compression and one rarefaction together make up wavelength.

Characteristics of sound Sound travel faster through liquids than through gases, and even faster through solids. The closer the molecules are in a substance the faster sound travel through that substance. The speed of sound is independent of its frequency.

added animation of a sound

• Electricity

Electricity[edit]

 Electricity lights up our homes, cooks our food, powers our computers, television sets, and other electronic devices. All matter is made up of atoms, and atoms are made up of smaller particles. The three main particles making up an atom are the proton, the neutron and the electron. Electrons spin around the center, or nucleus, of atoms, in the same way the moon spins around the earth. The nucleus is made up of neutrons and protons.Electrons contain a negative charge, protons a positive charge. Neutrons are neutral – they have neither a positive nor a negative charge.
 There are many different kinds of atoms, one for each type of element. An atom is a single part that makes up an element. There are 118 different known elements that make up every thing! Some elements like oxygen we breathe are essential to life. Each atom has a specific number of electrons, protons and neutrons. But no matter how many particles an atom has, the number of electrons usually needs to be the same as the number of protons. If the numbers are the same, the atom is called balanced, and it is very stable.
 Electrons can be made to move from one atom to another. When electrons move among the atoms of matter, a current of electricity is created. This is what happens in a piece of wire. The electrons are passed from atom to atom, creating an electrical current from one end to other.Electricity is conducted through some things better than others do. Its resistance measures how well something conducts electricity. Some things hold their electrons very tightly. Electrons do not move through them very well. These things are called insulators. Rubber, plastic, cloth, glass and dry air are good insulators and have very high resistance.
                               Closed and Open Circuits

Electricity must have a complete path from the power source. If this path is broken, the circuit is incomplete. An incomplete circuit is called an open circuit. Electricity can not flow unless the circuit is complete. A complete circuit is called a closed circuit.

                          Series and Parallel Circuits

Series wiring, the lights are connected in a way that current must pass through one bulb before it can get to the next. Parallel wiring, each bulb receives the current independent of the other bulbs.

• Magnetism

There are four well known strongly magnetic materials Iron Steel Nickel cobalt Objects that are attracted to a magnet commonly contain one or more of these four materials.

                                  Magnets

Magnets are either natural or manufactured. Natural magnets are commonly called lodestone. Manufactured magnets are made of special combinations of materials but must include one of the magnetic materials. Aluminum is often included because it is lightweight but still very effective. You can weaken a magnet by striking it with a hard object such as a hammer or by dropping it on a hard surface such as a concrete. Extreme heat, such as a torch, can effectively demagnetize a permanent magnet.

There were 3 chapters that did not have anything so i wanted to them on my own. so i started Waves/light and electricity/magnetism. By the next day people started to add more stuff.