All about atoms
Neutral vs
Charged Objects
Atoms are the
building block of matter. Atoms has different types called elements. Each
element are differentiated from each other by the number of protons that are
present in their nucleus, for example, an atom containing one proton is a
hydrogen (H) atom, an atom containing two protons is a helium (He) atom, an
atom containing three protons is a lithium (Li) atom, an atom containing eighty
protons is a mercury (Hg) atom, an atom containing one hundred and eighteen
protons is an ununoctium (Uuo) atom, and so on. The nucleus is surrounded by
electrons, the number of electrons that surrounds the nucleus is the factor
that determines
whether an atom is electrically charged or electrically neutral.
A positively charged atom has more protons than
electrons, a negatively charged atom has more electrons than protons, whereas
an uncharged atom has the same amount of electrons and protons.
An atom is described as being a small core of
protons and neutrons surrounded by electrons. The protons are tightly bound
within the nucleus and cannot be removed by ordinary measures, whereas the
electrons are attracted to the protons of the nucleus. Similarly, electrons
within atoms of other materials can be persuaded to leave their own electron
shells and become members of the electrons shells of other atoms of different
materials In other words, electrons are migrants, which are constantly on the
move and always ready to try out a new atomic environment and they are always
ready to adapt with the new atomic environment.
All objects on earth consists of protons, neutrons
and electrons. The electrons contained within the objects are often moving into
other objects. The process of an electron leaving one material object to reside
in another object is a commonplace. Objects that are charged contain unequal
numbers of protons and electrons. Charged objects have an imbalance of charge,
either more negative electrons than positive protons or vice versa.
The charge of an object is measurable, the unit is
called Coulomb. Just as mass is measured in grams or kilograms, just as
distance is measured in centimetres, metres or kilometres, just as volume is
measured in mililitres or litres, charge is measured Coulombs (abbreviated C).
The units of microcoulombs or nanocoulombs are more commonly used due to one
coulomb being an abnormally large quantity of charge. To illustrate the
magnitude of 1 Coulomb, an object would need an excess of 6.25 x 1018
electrons to have a total charge of -1 C, on the other hand, an object with a
shortage of 6.25 x 1018 electrons would have a total charge of +1 C.
The unit coulomb is named after the French physicist, Charles-Augustin de Coulomb
Sources :
Charging by induction
Friction is not the only way of charging an object,
but it is common. Induction is the way of charging an object without touching
the object to another charged object. An understanding of charging by induction
requires a good understanding of the nature of the conductor and an
understanding of the polarization process.
The induction charging of two metal spheres is an
example of a common demonstration performed in a physics classroom. Changes
acquired by the spheres cannot travel to the ground because the insulating
stands support the metal spheres.
The law of conservation of change is easily observed
in the induction charging process. Before the charging process, there was no
change of the system. The number of protons and electrons within the two
spheres in diagram ii is exactly the same. The point where the individual
spheres become charged are when the electrons were induced into moving from
sphere A to sphere B. The quantity of the positive charge on sphere A is exactly
the same with the quantity of the negative charge on sphere B. If sphere A has
1000 units of positive charge; then sphere B has 1000 units of charge, if
sphere A has 68,000 units of positive charge; then sphere B has 68,000 units of
charge, if sphere A has 666,000 units of positive charge; then sphere B has
666,000 units of charge, whatever the quantity of the units of positive charge
in one sphere, the quantity of the units of negative charge in another sphere
is exactly the same, as simple as that. The overall change of two spheres is
always zero.
The induction changing process can also be used to
charge a pair of tin cans. That experiment is simple, so it can be tried at
home. Two pop cans are mounted on Styrofoam cups using scotch tape. The cans which
has been rubbed by animal fur are placed side-by-side and a negatively charged
rubber balloon is brought near to one of the cans.
Coulomb’s law
The
interaction between charged objects is a non-contact force that acts over some
distance of separation. Charge, charge and distance. Every electrical
interaction involves a force that highlights the importance of these three
variables.
Like
all forces, the unit of electrical forces is called the Newton. Because it is a
force, the strength of the electrical interaction is a vector quantity that has
both magnitude and direction. The direction of the electrical force depends on
whether the objects are charged with like or opposite charge and upon their
spatial orientation. Applying the fundamental rules of charge interaction,
which states that opposites attracts and likes repel, is the best way to
determine the direction of the electrical force.
Electrical
force also has a magnitude or strength. There are a variety of factors that
affects the magnitude of electrical force like in most types of forces. In
accordance with the fundamental rules of charge interaction, two like-charged
balloons will repel each other. The three variables can be changed in order to
alter the strength of their repulsive force. The magnitude of the force and the
distance between the two balloons is said to be inversely related.
The
Coulomb’s Law Equation states about the quantitative expression for the effect
of these three variables on electric force. According to the Coulomb’s law of
equation, the electrical force between two charged objects is directly
proportional to the product of the quantity of charge on the objects. In the
form of equation, it can be stated as
, where the Q1 stands for the the
quantity of charge on object 1, which is measured in Coulombs, the Q2 stands
for the quantity of charge on object 2 which is also measured in Coulombs, the
d stands for the distance of separation between the two objects which is
measured in meters. The k is a proportionality constant known as the Coulomb's
law constant.
Coulomb's
law is often used as a type of algebraic recipe to solve physics word problems
in physics classes, an example of a word problem using this method is:
Suppose that two point charges, each
with a charge of +5.00 Coulomb are separated by a distance of 5.00 metres.
Determine the magnitude of the electrical force of repulsion between them.
Given:
Q1
= 1.00 C
Q2
= 1.00 C
d
= 1.00 m
Find:
Felect = ???
Answer:
Felect
= k • Q1 • Q2 / d2
Felect = (9.0 x 109 N•m2/C2)
• (1.00 C) • (1.00 C) / (1.00 m)2, so Felect = 9.0 x 109
N = 9 billion N
Another
example:
Given:
Q1
= 1,000.00 C
Q2
= 1,000.00 C
d
= 1,000.00 m
Find:
Felect = ???
Answer:
Felect
= k • Q1 • Q2 / d2
Felect = (9.0 x 10,0009
N•m2/C2) • (1,000.00 C) • (1,000.00 C) / (1,000.00 m)2,
so Felect = 9.0 x 10,0009 N = 1036 N
Electric field intensity
Electric
field strength has both magnitude and direction, so it is a vector quantity.
The magnitude of the electric field strength is defined in terms of how it is
measured. Electric charge is usually depicted by the symbol Q, the force is
usually depicted by the symbol F and the electric field strength is usually
depicted by the symbol E. The formula for this rule is
.
In
accordance to the Coulomb’s law equation, the electric force between two
charges is directly proportional to the product of their charges and inversely
proportional to the square of the distance between their centers. We have been
talking about this thing in the previous chapter: which is http://www.physicsclassroom.com/Class/estatics/u8l3b.cfm.
The formulas for electric field strength can
be used to solve physics word problems, just like all other formulas in
physics. And also, it can also be used to guide our thinking about how can the
modification of one variable might/might not affect another variable. In
accordance to the inverse square law, the source charge Q creates the strength
of the electric field.
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