13 December 2017

Hole Current

What is hole current?

  • The missing electron in the crystal structure is called as hole. The conduction of current due to missing electrons is called as hole current. 
  • The covalent bonds in the semi conductor material breaks resulting some free electrons are generated.

10 December 2017

Law of Resistance


  • It is a defined as property of substance which oppose the flow of current through it. The SI unit of resistance is ohm ( Ω ). 
  • One ohm is defined as the resistance of conductor when one voltage applies between conductor resulting one ampere current flows through it. 

3 December 2017

Compare Silicon and Germanium

Why Silicon is Preferred over Germanium

  • The silicon and germanium both are semiconductor material. 
  • However silicon is mostly preferred as semiconductor as compared to germanium due to following reasons.

30 November 2017

Energy Band Diagaram ( Conductor, Semiconductor and Insulator )

Valance electrons or band

  • The electrons in the outer most orbit of an atom are called as valance electrons.
  • The valance electrons have highest energy. This band may be partially or completely filled. 
  • The partially filled band can accommodate more number of electrons.

27 November 2017

Atomic Structure

  • The scientist Neil Bohr explains the atomic structure. According to Neil an atom consists of positive charged nucleus and negative charged electrons revolve in circular orbit. 
  • The electrons can revolve around the nucleus in certain orbits. 

25 November 2017

Voltage Source and Current Source

Ideal voltage source

  • An ideal voltage source is one in which terminal voltage remains constant regardless current flow through its terminals. 
  • The ideal voltage source has zero internal resistance. The symbol for the ideal voltage source is shown in the Figure A.

14 November 2017

Speed Control of the DC Shunt Motor

  • The speed of DC motor is related to following equation
         N a Eb / F
         N = K ( V – IaRa ) / F
  • Therefore the speed of the DC motor can be controlled by varying