# Lesson 5 – Introduction to Circuits - Stambytes

Electronics - Devices

Nov 2, 2013 (4 years and 8 months ago)

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INTRODUCTION TO
CIRCUITS

Text 11.2: Page 448
-
453

Agenda

1.
What are Circuits?

2.
Drawing Circuits

3.
Types of Circuits

Series

Parallel

4.
Transistors

5.
Activity!

Learning Goals

By the end of this
class we should be
able to:

Draw and construct circuit diagrams based on given
diagrams or circuits

Compare and contrast
current and
resistance in series
and parallel circuits

What is a Circuit?

Circuit Diagrams

Standardized symbols, like a language, used to
communicate the parts of a circuit

Circuit Diagrams

It is very important these
diagrams are always
very neat and tidy!

Always use straight lines
drawn with a ruler

Always use right angles
when connecting corners

Series Circuits

Is a circuit in which the
components are arranged
one after another in a series

There is only one path through
which the electrons can flow

If any one part of the series is
damaged or
interrupted the
whole circuit cannot function

Resistance

The amount of current is
the same in all parts of
the
series

BUT if
you
resistors
you increase the resistance
of the whole circuit which
decreases the current

i.e. if you add a second
bulb both bulbs become
dimmer

Parallel Circuits

An electric circuit in which the
parts are arranged in which
the electrons can move along
more than one path

Points where the circuit
divides
and combine
are called
junctions

An interruption or break in one
part of one pathway does not
affect the other pathways in the
circuit

Parallel Circuits

A
dding
more resistors or
new
pathways
does not
affect the resistance in
any other pathway

In
contrast,
resistors in a parallel circuit
decreases the total
resistance of the circuit

Water Analogy

Think of the Water Analogy

The more
straws sucking
water the less resistance of
water (Parallel Circuits)

path with the smallest
resistance values

Therefore more current in paths
with lowest resistance

Summary Table

Hmmm….

Combinations

Series and parallel
can be combined

This is used when
designing circuits in

i.e. won’t put a light
in a series circuit
because if it burns out
fridge will go off

Transistors

Used to control voltage or currents

i.e
. to make
voltage/current larger
or smaller on either side of the
transistor

A tiny device that acts as a switch
or
amplifier to make
current or
voltage
greater

EX:
in microphones electric signals
are amplified to make
sound louder
by the circuit

T
ransistors

Transistors are also
known as
solid state
components