ELECTRIC CURRENT
Movement of charge or electrons is called electric current
Unit = A (ampere)
Formula I=q/t
I – current
q-no of charges
t – time
CONVENTIONAL CURRENT
The direction of conventional current is opposite to the direction of
movement of electrons
Why conventional current ?
Sometimes in batteries ,both positive(+) and negative(-) charges move
so by convention direction opposite to movement of electrons is taken
as direction of current
CONDUCTOR
Some materials have free electrons in their valence shell, when we apply
some energy these electrons starts to move
Eg : Copper
Valence of Cu is 1
TYPES
AC- Alternating current
DC – Direct current
DC
Charges flows in one direction
No polarity change
Cu = [Ar] 3d^10 4s^1
AC
Current changes its direction or electron changes its direction
Current changes its polarity at regular intervals of times
VOLTAGE
It is known as electric pressure ,work done to move electric charge
It is the difference in the electric potential between two points
Unit = V( volt)
Formula – V= IR(ohm’s law)
ELECTRIC FIELD
Electric field is the physical field that surrounds electrically charged
particles and exerts force on all other charged particles in the field, either
attracting or repelling them
Formula- E = F/Q(Nm^-1)
FREQUENY
Frequency is the number of occurrences of a repeating event per unit of
time
Unit – Hz
CAPACITOR
Device to store energy in the form of electric charge
Two conductors are separated by a distance
Space between them can be vaccum or an insulating material called
dielectric
The ability of the capacitor to store charges is called capacitance
Formula – C=q/V
INDUCTOR
Device to store energy in presence of magnetic field and electric current
flowing through it
Opposes any change in current
Whenever current, passes through it which changes with time , it
acquires charges or losses charges to equalize current passing through it
MAGNECTIC FIELD
Magnetic Field is the region around a magnetic material or a moving
electric charge within which the force of magnetism acts.
INSULATORS
Materials which do not conduct electricity are called insulators
They have high resistance and do not have any free electrons
SEMICONDUCTOR
Materials which having character between conductor and insulator are
called semiconductor
Eg: Silion
In semiconductor ,
Electrons are considered as negatively charged
Holes are considered as positively charged
A semi conductor can’t conduct electricity by pure semiconductor
It can conduct by adding impurites this process is called doping
Eg : Silion
Holes are places which have a tendency to attract a electron or positively
charged place
In a semiconductor if by doping
More electrons are formed that semi conductor is called
n-type
Holes are formed that semiconductor is called p-type
semiconductor
By giving some energy valence band electrons can be converted to
conductance band electron
PN JUNCTION DIODE
Diode are devices which allow current in only one direction
PN junction diode are p-type semiconductor and n-type semiconductor
In PN junction, a region called depletion region is formed ,since p-type is
positively charged and n-type is negatively charged there will be electron
transfer
After certain electron tranfer to the holes , the transfer of charges will be
stopped because of the opposition of the charges
In PN junction diode when p-type is connected to positive terminal of a
source and n-type is connected to a negative terminal it is called forward
biased current
The current flows through it
When p-type is connected to negative terminal and n-type is connected
to positive terminal it is said to be reverse biased current
The current doesn’t flows through it because it neutralises the electrons
and holes
LED- light emitting diode
It emits light when electricity flows through it
LEDs are typically small, efficient, and durable, and they are widely used in a
variety of electronic devices, such as smartphones, televisions, and traffic
signals. They are also increasingly being used as a replacement for traditional
incandescent and fluorescent lighting in both residential and commercial
applications. Due to their efficiency, long lifespan and environmental benefits,
LEDs are becoming the preferred choice for lighting solutions.