Active components
Active components supplies energy to the circuit. Active components can control the electron flow.
Examples:
Voltage Sources
Current Sources
Generators
Diodes
The atoms have a planetary type of structure according to the classical Bohr model.
All the protons and neutrons are bound together at the centre of an atom. Which is called nucleus. while all the electrons were moving around the nucleus.
In an atom the number of protons and the number of electrons are equal. The number of protons is called atomic number. Total number of protons and neutrons in the nucleus is called atomic weight.
Electrons revolving around the nucleus do not more in the same orbit(Shell). Each shell contains fixed number of electrons. A shell can contain maximum of 2n2 electrons.
Electrons closer to the nucleus has high force of attraction and electrons farther from the nucleus has less force of attraction. Show the electrons in the outer shell has loosely bonded to the nucleus.
the amount of energy required to extract the valence electrons from outer shell is very less.
When an atom absorbs energy from external source, its energy levels increases and electron moves to the next orbit. If such external energy is observed by valence electron, it tries to move to next orbit but there is no next orbit so it is completely removed from the force of attraction of nucleus.
According to the modern electron theory, matter is composed of three fundamental particles. these are neutron proton and electron.
Proton is positively charged.
Electron is negatively charged.
Neutron is uncharged.
The mass of neutron and proton is same.
|
Fundamental Element |
Nature of Charge |
Mass in Kg |
|
Neutron |
No
Charge |
1.675 x
10-27 |
|
Proton |
Positive |
1.672 x
10-27 |
|
Electron |
Negative |
9.107 x
10-31 |
There is no difference between an electron of copper and an electron of aluminium or an electron of any other element. similarly the neutrons and protons of various atoms or characteristic wise identical in nature.
Some materials allow current to pass through them, some materials not allow current to pass through them.
Materials which allow current to pass through them are called conductors. Copper aluminium are the best examples for conductors.
Materials which will not allow current to pass through them are called insulators. Wood plastic paper are the examples for insulators.
Where is another class of materials which have the ability to carry the current lies between conductors and insulators are called semiconductors. Silicon and germanium examples semiconductors.
