Current, Voltage, and Power
The charge of an electron is qE = -1.602x10-19 C
Conservation Law: Charge can neither be
created nor destroyed, but it is mobile and can
be transferred from one
Circuits and Devices
Schematic Diagrams and Symbols
A circuit is a collection of interconnected
electrical devices such that charge (usually
electrons) can flow through it continuously
without beginning or end.
Resistance and Conductance
The amount of resistance to current is
measured in ohms () and is represented by
the letter R.
The reciprocal of resistance is conductance
measured in siemens (S) and repres
A two-terminal device is described by its i-v
In the simplest case the i-v characteristic is a
graph of i versus v.
Example: i = v/R
Current i through R
A capacitor consists of two metal plates
separated by a dielectric with permittivity .
Values for small capacitors range from 10 pF
(1 pF = 10-12 F) to several 100
Frequency Response of RC
RC Circuit 1
Vs is source voltage
(sine, 1000 Hz,
amplitude 1 V).
Vc is voltage across
Input and Output Signals:
Output signal (blue)
has almost same
Voltage and Current Markings
The voltage and current marks shown use the passive sign
convention for the load
For the sources the active sign convention is used.
Modern diodes and transistors are made from
semi-conductive materials (conductivity in
range of 103 to 10-8 S per cm).
Typical semi-conductive materials are silicon
(Si), germanium (Ge)
Atoms and Charge
Example: Lithium (Li) Atom
The atom is considered to be the basic building
block of matter.
Atoms consist of a nucleus, made up from
protons and neutrons, and electrons.
Protons have positive elec
There are two major families of transistors:
Bipolar junction transistors (BJT) and fieldeffect transistors (FET).
BJTs have 3 terminals and come in two
varieties, as NPN and PNP transisto