CURRENT:
An electrical phenomenon is caused
by flow of free electrons from one atom to another. The characteristics of current
electricity are opposite to those of static electricity.Wires
are made up of conductors such as copper or aluminum. Atoms of metal are made
up of free electrons, which freely move from one atom to the next. If an
electron is added in wire, a free electron is attracted to a proton to be neutral.
Forcing electrons out of their orbits can cause a lack of electrons. Electrons,
which continuously move in wire, are called Electric Current.
For solid conductors, electric current refers to directional
negative-to-positive electrons from one atom to the next. Liquid conductors and
gas conductors, electric current refers to electrons and protons flow in the
opposite direction.
Current is flow of electrons, but current and
electron flow in the opposite direction. Current flows from positive to
negative and electron flows from negative to positive.
Current is determined by the number
of electrons passing through a cross-section of a conductor in one second.
Current is measured in amperes, which is abbreviated "amps".
The symbol for amps is a letter "A".
A current of one amp means that current pass
through a cross-section of two conductors, which are placed in parallel 1 meter
apart with 2x10-7 Newton per meter force occur in each conductor. It
can also mean charges of one coulomb (or 6.24x1018 electrons)
passing through a cross-section of a conductor in one second.VOLTAGE:
Electric
current is flow of electrons in a conductor. The force required to make current
flow through a conductor is called voltage and potential is the
other term of voltage. For example, the first element has more positive
charges, so it has higher potential. On the other hand, the second element has
charges that are more negative so it has lower potential. The difference
between two points is called potential difference.
Electromotive force means the force which makes current continuously flows through a conductor. This force can be generated from power generator, battery, flashlight battery and fuel cell, etc.
RESISTANCE:
Electrons move through a conductor
when electric current flows. All materials impede flow of electric current to
some extent. This characteristic is called resistance. Resistance
increases with an increase of length or decrease of cross-section of a
material.
The unit of measurement for
resistance is ohms and its symbol is the Greek letter omega (Ω).
The resistance of one ohm means a conductor allows a current of one amp to flow
with a voltage of one volt.
All materials are difference in allowing electrons flow. Materials that allow many electrons to flow freely are called conductors such as copper, silver, aluminium, hydrochloric solution, sulphuric acid and saltwater. In contrast, materials which allow few electrons to flow are called insulators such as plastic, rubber, glass and dry paper. Another type of materials, semiconductors have characteristics of both conductors and insulators. They allow electrons to move while being able to control flow of electrons and examples are carbon, silicon and germanium.
All materials are difference in allowing electrons flow. Materials that allow many electrons to flow freely are called conductors such as copper, silver, aluminium, hydrochloric solution, sulphuric acid and saltwater. In contrast, materials which allow few electrons to flow are called insulators such as plastic, rubber, glass and dry paper. Another type of materials, semiconductors have characteristics of both conductors and insulators. They allow electrons to move while being able to control flow of electrons and examples are carbon, silicon and germanium.
The resistance of conductor depends
on two main factors as the followings:
1.
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Types of material
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2.
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Temperature of material
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