LECT#2_ELECTRON_THEORY.pdf

ELECTRICAL CIRCUITS / ELECTRICAL ESSENTIALS AND NETWORKS D.A.E 1ST YEAR (ELT/BM/MTR) BY ENGR. SIDRA AZIZ EL.TR-114/ ELT-114/ 1 ELT/BM/MTR - 1ST YE...

ELECTRICAL CIRCUITS / ELECTRICAL ESSENTIALS AND NETWORKS D.A.E 1ST YEAR (ELT/BM/MTR) BY ENGR. SIDRA AZIZ EL.TR-114/ ELT-114/ 1 ELT/BM/MTR - 1ST YEAR MTR-132 BY: ENGR. SIDRA AZIZ 2 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  BASIC PRINCIPLES OF ELECTRICITY CHAPTER 1: 3 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  DIFFERENCE BETWEEN AC AND DC AC DC ALTERNATING CURRENT DIRECT CURRENT Changes direction periodically Only flows in one direction Have both positive and negative Can have single polarity polarity Sources: Main supply, Generators Sources: Batteries,Cells, Solar panels Types: Sinusoidal,Traingular,Square etc Types: Regulated (fixed), Pulsating 4 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  DIFFERENCE BETWEEN AC AND DC REGULATED PULSATING AC DC DC 5 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  STRUCTURE OF ATOM PROTON ELECTRON NEUTRON SHELLS 6 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  SHELLS/ORBITS The maximum number of electrons a shell can hold is 2n2. SHELL LETTER NO. OF ELECTRONS NUMBER SYMBOL 1 K 2n2 = 2 x 12 = 2 2 L 2n2 = 2 x 22 = 8 3 M 2n2 = 2 x 32 = 18 7 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  VALENCE SHELL AND VALENCE ELECTRON VALENCE SHELL: The outer most shell of any atom is called valence shell and the electrons in that shell are called as valence electrons. VALENCE VALENCE 8 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ SHELL ELECTRON  FREE ELECTRONS FREE ELECTRON: Valence electrons are loosely attached to the nucleus of a atom. When small amount of external energy in form of heat or light is applied to the valence electrons then they get pulled away from the parent atom and becomes free. These electrons are called free electrons. 9 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  TODAY' S SUMMARY Difference between AC and DC Electron Theory Structure of atom Shells and maximum number of electrons in each shell Valence shell and valence electrons Free electrons 10 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ  THANKS 11 ELT/BM/MTR - 1ST YEAR BY: ENGR. SIDRA AZIZ