Electricity: Basic Concepts, Circuits, and Ohm's Law for High School Physics

Electricity Fundamentals

U4
ELETRICITY
1
Electricity.
Electrica
energy
atoms
electrons (-)-electron
Shell
A
protons
(+
nucleus
neutrons
Nº electrons = No protons
· forces of attraction or repulsion
electric charges- ¥
or
=
· electrical current = Movement
of
electrons
= electricity
· energy!
electrical energy
light
heat
- motion
> sound

Electrical energy is transformed into
heat, sound or mechanical energy in
radiators, bells or motors.

Electrical Energy Conversion

How can electrical energy be converted to other forms of
energy?2

Conductors and Insulators

Conductors and insulators
materials
insulating materials
do not let electric current flow through
conducting
materials
them
let electric current flow
through them
3

Electric Circuits and Components

Electric circuits. Components

Power Sources

Supply
Power sources
the necessary
electrical
energy to the rest of the circuit
+
+
+
I
Cell
Battery

Conductors

Conductor
· Transport the electrical energy
through the circuit
wire

Load Devices

Load devices
Convert
the
electrical energy
to
light, heat, sound , movement ...
M
lamp
motor
buzzer
resistor
engine

Control Devices

Control
devices
· Opens or closes the circuit
-
NO Switch
(normally open)
NC Switch
(normally closed)
NO push button
(normally open)
1
NC push button
(normally closed )cell
NO switch
0-
lamp
NC push button
motor
M
NO push button
0
buzzer
Single two-way
switch
0
NC switch
-Control devices
1
single two-way
switch
double two-way
switch
21

Representing Circuits: Electrical Schematics

Representing circuits: electrical
schematics
electrical schematic =>
every component
III1
Standardised
Symbol5

Open, Closed, and Short Circuits

Open circuits and closed circuits
short
circuits
· Open circuit
the electric current
cannot flou
· Closed circuit __ the electric current
flows
0
. Short circuit- the electric current
without
is transported
by the wire
passing throught a load device
+
-X 1000
x 1000
KA
A
MA
KV
V
mV
m_2
: 1000
KR
: 10006

Main Electric Variables and Ohm's Law

Main electric variables. Ohm's law

J= I.R
I
R
I= V
R
R=
>/H
I7.

Types of Circuits: Series, Parallel, and Series-Parallel Combination

Types
of
circuits: series, parallel and
Series-parallel combination

Series Circuits

Series
circuits
IT
+
VT
T
V2
V
3
. IT= I1 = I2= I3
( the same current flows through
all the load devices )
· VT=VI+V2+V3
. One load device stop > all
working
stop
working
· Energy supplied by the cell is shared
among all three
Lamp's will not
be very bright

Parallel Circuits

Parallel
circuits
+
IT
FT
Iz
I3
IT = +1++2++3
VT= V1 = V2 = V3
.
the
One load device stops => rest
working
continue working
The Camps will shine very
brightly because the energy from the
cell reaches them directly

Series-Parallel Combination Circuits

Series-parallel
combination
circuits
18

Solving Circuits

Solving
circuits
· Association of resistors
(R1, R2, R3)
(series or parallel)
· Total resistance = RT
1
· Equivalent circuit

Resistors in Series

Resistors in series
R1
R2
RT
V
RT =R1+R2

Resistors in Parallel

Resistors in parallel
R
RT
R2
N
RT=
R1. R2
R1+ R29

Converting Electrical Energy

Converting electrical
energi
.
Resistor
converts
HEAT
electric
energy
to heat
energy
Lamp
light
energi
LIGHT
· Motor
11
11
11
Kinetic
energy
MOTION
· Buzzer 11
11
1
FOUND
round
en
energy10

Energy and Environment

Energy and environment
· The use of renewable energies is being
promoted
· Replace Incandescent bulb with low energy
bulbs
bul
· Use certain domestic appliances only when
they are
Pull
· Replace old electrical appliance with
more efficient ones labelled "class "
(consume less energy)
· Always switch off electronic equipment
instead
leaving
them in standby
of
mode