Charged particle
From ArticleWorld
In physics, a particle that possesses an electric charge is said to be a charged particle. The charge may be present either in a subatomic particle such as an electron or in the form of an ion. The presence of a collection of charged particles, which may be in the form of a gas containing a proportion of charged particles, is referred to as plasma. The state of plasma is said to be the fourth state of matter because of the fact that it possesses properties that differ from those of the three states of solid, liquid and gas.
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Common charged particles
Some of the commonly known charged particles are described below:
Alpha particle
An alpha particle is the nucleus of a helium atom, represented with the symbol 'He', with a mass number of 4 and an atomic number of 2. Thus, with 2 protons and 2 neutrons, it possesses a positive charge of 2. Alpha particles are emitted by radioactive materials during their decay and tend to lose their energy when they collide with other particles. These particles have low penetrating power and are obstructed by a sheet of paper or the outer layer of the human skin. However, they can cause damage to internal organs if they are present inside the body.
Beta particle
A beta particle is in fact an electron that is emitted by certain radioactive nuclei by the phenomenon of beta decay. They possess a negative charge, which is -1, and is denoted by 'e'. They can travel up to a few meters in air, a distance more than that which alpha particles can travel. Beta particles have a penetrating power that is greater than that of alpha particles and lesser than that of gamma radiation. Beta radiation can be stopped by a thin sheet of aluminum or wood. These particles can cause considerable biological damage if they are incident in sufficient levels.
Positron
A positron is the antiparticle of an electron, emitted during positron radioactive decay. It is denoted by 'e' and possesses a positive charge. It has other properties which are identical to those of an electron. When a positron annihilates an electron, two gamma ray photons are formed.
Plasma – The fourth state of matter
The term 'plasma' refers to an ionized gas, possessing free electric charges that allow the conduction of electricity. This state can be induced by strong electric fields or by intense heating, which causes electrons to be removed from atoms, thus allowing positive and negative charges to travel freely in the plasma.
Plasma is the most abundant form of matter in the universe. It is found in the stars and interstellar nebulae. On the earth, the plasma state occurs in the ionosphere and is seen to occur during lightning. Artificial induced plasma is seen in applications as diverse as the plasma television and research aimed at fusion energy.