Electrical Charge
Electrical charge is a
fundamental quantity and is intrinsic property of matter which causes a force
to act between particles (objects, bodies..) which have this property. It is physical
quantity which can be transferred from one object to another.
Electric charge comes in two
types, which wechoose to call positive charge and negative charge.
Electric charge can be measured
using the law for the forces between charges (Coulomb’s Law). Charge is a scalar
and is measured in coulombs. The coulomb is actually defined in terms of
electric current (the flow of electrons), which is measured in amperes; when the
current in a wire is 1 ampere, the amount of charge that flows past a given
point in the wire in 1 second is 1 coulomb. Thus,
when charges are transferred by
simple interactions (i.e. rubbing), it is a negative charge which is
transferred, and this charge is in the form of the fundamental particles called
electrons. The charge of an electron(e) is -1.6022 × 10-19 C.
The particles found in nature all
have charges which are integral multiples of the elementary charge e:
q = ne where n = 0, ±1, ±2 . . .. Because of
this, we say that charge is quantized.
A charged object is an object that has an excess of one type
of charge, e.g., more positive than negative. The amount of excess charge is
the charge we assign to that object.
Current
Flow of charge moving through unit area in unit time. It represents charge transfer.
Voltage/Potential Difference
Voltage is
a measure of the energy carried
by the current. Technically it is a measure of the difference in energy between
two points – hence the name potential
difference. Voltage represents potential difference between two points. It
represents work to be done to move unit charge from one point to other under
influence of electric field.
