Secondary 1 Term 2 Science ACE Project:
PLASMA
By: Jerroy Chang (4) of 1I3
What is plasma?
Plasma is known as the fourth state of matter, apart from the three basic states, solid,
liquid and gas. Plasma is, in simple terms, ionized gas. It is mainly exciting a gas until it
breaks up into individual atoms, and some of those atoms lose their electrons, turning
into positive ions. These electrons and positive ions both make up plasma. The
excitement of the gas uses energy, which can come in 3 forms: thermal, electrical, or
light.
Origin:
The first scientist who found this fourth state of matter is Sir William Crookes, a
British chemist, in 1879. He found plasma in his own invented tube, the Crookes tube.
Later, in 1929, Dr. Irving Langmuir, an American chemist, declared that fourth state of
matter as “Plasma”.
Plasma and the Universe:
Plasma is the most common form of matter. It makes up over 99% of the visible
universe. Plasma can be found in the stars and the space between planets and stars,
such as our Sun.
Plasma particles:
The plasma particles are usually arranged in little or no
order. They are allowed to move freely under the
influence of a magnetic field. However, plasma
particles generate electrical currents with magnetic
fields, and therefore, they are affected by each
other’s magnetic fields, somewhat limiting their
movements.
Properties of plasma:
Plasma is a good conductor of electricity.
Plasma is affected by magnetic fields.
Uses of plasmas
Plasma is used in fluorescent tubes. Electricity excites the mercury vapor in the tube,
and therefore ionization occurs, leading to the change in state from gas to plasma.
Therefore, the mercury vapor gives off a white glow. Plasma can also be found in neon
signs, where noble gases such as neon, krypton and xenon are excited to form different
colours. Plasma displays are another way plasma is used, such as in plasma TVs, when
varying electrical volts excite gases to turn into different colours, creating an image on
the screen.
Another use of plasma is the plasma ball. The plasma
ball is a sphere that is filled with (noble) gases.
When these are excited by an alternating current,
plasma filaments are created. Plasma balls are now
mainly decorative items.
Where else are plasmas found?
They can be found in lightning. Negative ions move down from
the thunderclouds towards the earth. When they strike the
earth, an ionized chamber is created. The return stroke
occurs, sending up a huge charge from the earth back to the
thundercloud, discharging plasma. They can also be found in
ball lightning, a sphere-shaped ball containing lightning.
St. Elmo’s fire is another place where plasma can be found. St. Elmo’s fire is a mix of
gas and plasma. An electric field excites the air molecules, producing a faint glow
around objects.
Plasma can also be found in the aurora at the Northern and Southern poles. The ionized
gas is funneled down the Earth’s magnetic field lines. After that, they will emit a
photon of light, thus causing the aurora.
Electric arcs are also another form of plasma that results when an electric current is
flowing through the air, exciting the air and effectively ionizing it. Therefore, plasma
forms in the gap between the wires.
Lastly, plasma can be found in stars such as our Sun, solar wind, nebulas and space.
~The End~