Relationship Between Voltage, Current Resistance :-
All materials are made up from atoms, and all atoms consist of protons, neutrons and electrons.
Protons, have a positive electrical charge. Neutrons have no
electrical charge while Electrons, have a negative electrical charge. Atoms are bound
together by powerful forces of attraction existing between the atoms nucleus and the electrons in its outer shell.
When these protons, neutrons and electrons are together within the atom they are happy and stable. However, if we
separate them they exert a potential of attraction called a potential difference. If we create a circuit
or conductor for the electrons to drift back to the protons the flow of electrons is called a current.
The electrons do not flow freely through the circuit, the restriction to this flow is called resistance.
Then all basic electrical or electronic circuit consists of three separate but very much related quantities,
Voltage, ( v ), Current, ( i ) and
Resistance, ( Ω ).
Voltage :-
Voltage, ( V ) is the potential energy of an
electrical supply stored in the form of an electrical charge. Voltage can be thought of as the force that pushes electrons
through a conductor and the greater the voltage the greater is its ability to "push" the electrons through a given circuit.
As energy has the ability to do work this potential energy can be described as the work required in joules to move electrons
in the form of an electrical current around a circuit from one point or node to another. The difference in voltage between
any two nodes in a circuit is known as the Potential Difference, p.d. sometimes called Voltage Drop.
The Potential difference between two points is measured in Volts with the circuit
symbol V, or lowercase "v", although Energy, E
lowercase "e" is sometimes used. Then the greater the voltage, the greater is the pressure
(or pushing force) and the greater is the capacity to do work.
A constant voltage source is called a DC Voltage with a voltage that varies periodically with
time is called an AC voltage. Voltage is measured in volts, with one volt being defined as the electrical pressure
required to force an electrical current of one ampere through a resistance of one Ohm. Voltages are generally expressed
in Volts with prefixes used to denote sub-multiples of the voltage such as microvolts
( μV = 10-6 V ), millivolts
( mV = 10-3 V ) or kilovolts
( kV = 103 V ). Voltage can be either positive or negative.
Batteries or power supplies are mostly used to produce a steady D.C. (direct current) voltage source
such as 5v, 12v, 24v etc in electronic circuits and systems. While A.C. (alternating current) voltage sources are
available for domestic house and industrial power and lighting as well as power transmission. The mains voltage supply
in the United Kingdom is currently 230 volts a.c. and 110 volts a.c. in the USA. General electronic circuits
operate on low voltage DC battery supplies of between 1.5V and 24V d.c. The circuit symbol for a constant voltage source
usually given as a battery symbol with a positive, + and negative, -
sign indicating the direction of the polarity. The circuit symbol for an alternating voltage source is a circle with a
sine wave inside.
Voltage Symbols
