Download Simple Circuits lecture

Electronics Introduction
FOR BHS PHYSICAL SCIENCE
9 TH G R A D E
What is Electricity
 What does Electricity mean to you?
 Where does it come from, how does it work?
Electricity
 It is the many physical quantities and properties
associated with electrical charges.
 This area of science is responsible for all electronics
devices and an integral part to all modern science.
Types of Charges
 Electricity is dependent at two main types of charges
positive and negative.
 Electrons are particles that have the negative charge
and are free to move in atoms.
Electric Force
 Opposite charges repel and like charges attract
 This electric force increases based on distance and
larger amounts of charge.
Electric Field
 Electric field also depends on the distance and
amount of charge like electric force.
Current (I)
 Current is the flow of charged particles (usually
electron)
 Currents symbol is I and it’s units are in ampere’s
often abbreviated as A.
 Two main types of current exist AC and DC
AC vs. DC
 DC means direct current and is when charge
particles only flow in one direction.
 AC means alternating current and is when current
changes direction periodically. (This means it has
wave like properties)
Resistance (R)
 Resistance is the opposition to the flow of charges in
a material (aka current).
 Resistance is dependent on the material, it’s length,
thickness and temperature.
Conductors
 Conductors have a relative low resistance and thus
readily conduct current.
 Good thermal conductors are almost always good
electrical conductors. So, copper, aluminum, etc. are
good conductors.
Insulators
 Insulators have a rather high resistance and thus
gives current a hard time.
 Thermal insulators are again often electrical
insulators. So, wood, rubber and air are good
insulators.
Voltage (Potential Difference)
 A difference in energy between two locations that
allows current to flow. (So, if Voltage equals 0 there
can be no current)
 Voltage (V) is measured in Volts and named after an
Italian Physicist Volta who invented one of the first
batteries.
Ohm’s Law (VIR)
 Ohm’s law is the simple linear relationship between
voltage to current and resistance. V = I R
 This equation is a foundation to analyzing circuits.
Such as for example, V= I R gives (9 V) = I (100 Ω)
which yields I= 9 V/ (100 Ω) = 0.09 Amps for the
circuit below.
Electric Power (PIV)
 Electric Power is equal to current times voltage. So,
P= I V
 This means that for the previous circuit, with a
voltage of 9 V and current of 0.09 A,
that power is P = (9 V) (0.09 A) yields P = 0.81 Watts
Static Electricity
 Is the build up of electrical charge on an object.
 This objects can build up charge by friction, contact
and induction.
Contact Charging
 By using friction you can exchange electrons with an
object thus building a net charge.
 By contact with a charged object, you can drain the
charge to you.
Magic?
 By bringing a charged object near a non-charged
object, you can cause the non-charged object attract
the charged object!
 What is this magical phenomenon, you may ask?
Induction
 We call this induction and it occurs by the free
electrons of the non-charged object rearranging in
such a way to produce an apparent charge. Although,
the non-charged object is still neutral.
Circuit Diagrams
 Circuit diagrams use symbols to represent parts of
the circuit.
 This is basically a blue print for how to build a
devices electrical part.
Series Circuit
 If one element in a series circuit stops functioning,
all elements stop.
 Not useless! If a circuit stops functioning during a
power surge it can save the other elements.
Parallel Circuit
 If one element in a circuit stops functioning, the rest
can still operate.
 This is how a homes fuse box is wired.
Grounding (Earth Ground)
 Grounding is when a wire goes directly into the
earth.
 The earth is ideally a giant conductor and thus soaks
up the current that goes to it.
 Used as a safety for open circuits. If a device short
circuits the earth is a better conductor than you are
and thus the charge goes to it instead of you!
Fuse
 A fuse is an electrical component that melts down
and protects the rest of the circuit from power
surges.
 This can stop your home’s electrical components
from exploding during a power outage.
Electronics Devices!
 The science of using an electrical signal to transmit,
process or store information is electronics!
Types of Signal
 Two main types:
 Analog signals which can vary both in amplitude and
frequency. (Yes, waves are back to haunt you)
 Digital which have two states for amplitude high and
low or rather 0 and 1. Binary signals.
Semiconductors
 A magical material that can be both an insulator or
conductor under certain conditions.
 This material allows for some of the most important
electrical components to modern life.
Solid-State Components
 Modern technologies heart! The vital foundation for
computers, cell phones, iDevices, etc.
 Three types we will cover:
 Diodes, Transistors and Integrated Circuits
Diodes (d)
 Only allow current to flow in one direction.
 This allows you to convert AC to DC current.
Transistors (Q)
 Can be used as electronic switches, amplifiers, a
changing resistor and much much more.
 These in particular, are responsible for all
computers!
Integrated Circuits (IC)
 These marvelous components are simply many
components built on a silicon chip and thus are
extremely small.
 IC’s are often just many transistors combined.