ELECTRONICS

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2

of 41

INTRODUCTION

TO ELECTRICITY

AND ELECTRONIC

CIRUITS

C B E M C - 1

Prepared by: Hiroki Asaba

LECTURE

BASIC CONCEPTS OF ELECTRICITY

ATOMS

PROTONS

Positively Charged

Atoms are composed of three types of particles: neutrons, protons, and electrons.

NEUTRONS

No Charge

ELECTRONS

Negatively Charged

Orbits the nucleus

Copper atom:

• Protons = 29

• Electrons = 29

• Neutrons = 35

Electrons flow around the nucleus

in electron orbital shells.

Electrons in the more outer layers

of the shell are more loosely bound

to the atom.

The outermost layer of the shell is

called the valence shell.

With enough force, electrons can

escape the atom and become free

electrons.

FREE ELECTRONS

Electron Shell:

• 1st Shell = 2

• 2nd Shell = 18

• 3rd Shell = 8

• 4th Shell = 1

(Valence Shell)

of free electrons

Electrons carry a charge of -1e, and

protons carry a charge of +1e.

“e” refers to an electron unit

ELECTRIC CHARGE

Proton

Electron

Charge

+1e

-1e

The unit for electric charge is Coulomb (C)

1 Coulumb = 6,250,000,000,000,000,000e or 6.25 × 10 electron units

Therefore,

1

8

1 electron = -1C / 6.25 × 10 1

8

-

19

1 proton = +1C / 6.25 × 10 1

8

-

19

CONDUCTIVITY

Some substances can transfer electric charge when applied enough force.

This force is called the electrostatic force and allows electrons to flow from

atom to atom.

Electrical conductivity measures how easy it is for the electrons to be

transferred

CONDUCTORS

Elements with high conductivity, which means

they easily transfer electric charge

INSULATORS

Elements with low conductivity, which means

they does not transfer electric charge

Copper Wire w/ Insulation

Describes the electrostatic force between charges

Charges of similar types repel

Charges of opposing types attract

The closer the charges, the stronger the force.

COULOMB’S LAW

Proton

Electron

F

k

q , q

r

= electric force

= Coulomb constant

= Charges

= distance of separation

r r

q q q q1 12 2 21

Coulomb constant:

8.99 × 10 Nm /C9 2 2

Where:

ELECTRICITY

Electricity is the phenomenon associated with