2. Define current, voltage
and resistance.
Today, you’ll
be able to:
Learn about capacitor, inductor,
diode, transistor
Calculate for current,voltage and
power
Relationship between current,
voltage and resistance through
Ohm’s law
Digital Logic Circuits
The Elements of Electricity
3. e
electrons
wire
When a charger is plugged in,
negatively charged particles called
electrons, which are already present
inside the wires, start moving in the
same net direction.
This flow of electrons is what we call
electric current. The voltage, or
electrical pressure pushes these
electrons along the wires.
e
e
e e
e
electric current
4. electrons
wire
Free electrons move along a zigzag
path, colliding with each other and
with fixed atoms within the material,
creating resistance.
This resistance makes the wire and any
connected devices, like your phone
charger, heat up.
e
electric current
5. BULB
Current
Current (measured in amps or amperes,
A) is the rate of flow of charge in a circuit.
This flow is in the form of electrons flowing
through a circuit.
An ammeter is used to measure current. It
is always connected in series with the
circuit.
There are two types of current.
i) Direct Current (DC)
ii) Alternating Current (AC)
BATTERY
A
M
M
E
T
E
R
7. Calculating Current
Electric current is the amount of charge passing through a
component per second. This relationship between current,
charge, and time is expressed by the equation:
i
Q
t
Current, measured in amperes (A)
Charge, measured in coulombs (C)
Time, measured in seconds (s)
current ( i ) =
charge ( Q )
time ( t )
8. Calculating Current
Calculate the current in an air conditioning unit that has
a charge of 18,400 C flowing through it every hour.
STEP 3: SUBSTITUTE THE VALUES. STEP 4: SOLVE.
current ( i ) =
18,400 C
3,600 s
EXAMPLE
= 5.1 A
current ( i ) =
18,400 C (Q)
3,600 s ( t ) Answer:
The current in an air conditioning unit that has a charge
of 18,400 C flowing through it every hour is 5.1 A.
9. BULB
Voltage
Voltage (measured in volts, V) is the
pressure or push behind the flow of current.
It is also referred to as potential difference.
A voltmeter is used to measure voltage. It
is placed parallel to the component(s) to
measure the voltage
in a circuit.
BATTERY
A
M
M
E
T
E
R
S
W
I
TC
H
VOLTMETER
10. Resistance
Resistance (measured in ohms, Ω) is a measure
of how much a material opposes the flow of
electric current going through it.
The greater the resistance, the more energy is
needed to push the current through the
component, which can affect the overall
performance of electrical circuits.
An ohmmeter is used to measure the amount of
resistance present when a current is passed
through a particular component.
RESISTOR
OHMMETER
Ω
11. Ohm’s Law
Ohm's Law states that the current through
a conductor is directly proportional to the
potential difference across it, provided the
temperature remains constant.
current ( i )
=
Voltage ( Q )
Resistance ( Ω )
12. Ohm’s Law
Calculate the voltage, or potential difference, through a resistor with a
resistance of 40 Ω with a current of 0.6 A flowing through it.
STEP 3: SUBSTITUTE THE VALUES. STEP 4: SOLVE.
EXAMPLE
Answer:
The voltage through a resistor that has a resistance of 40
Ω with a current of 0.6 A flowing through it is 24 V.
V = i × Ω
V = 0.6 A × 40 Ω
V = 0.6 A × 40 Ω = 24 V
13. Summary
Current Voltage Resistance
Current is the rate of flow
of charge in a circuit. This
flow is in the form of
electrons flowing through
a circuit.
Current is measured in
amperes (A) using an
ammeter.
Voltage is the pressure or
push behind the flow of
current. It is measured in
volts (V) using a voltmeter.
Voltage is also referred to
as potential difference.
Resistance opposes
current flow and is
measured in ohms (Ω). It
can be calculated by
dividing the voltage by the
current.
14. What is an electric circuit?
DIRECTION OF
ELECTRIC CURRENT
It is a complete path
through which electric
current flows.
It should be
constructed in an
unbroken loop.
15. Switch off Switch on
Switch on
Type of Circuits
Simple Open Circuit Simple Closed Circuit
Parallel Circuit
Series Circuit
Short Circuit
16. What is
Power? Electric power is the rate of transfer of
electrical energy within a circuit.
SI unit: Watt(W)
Formula :Power=Voltage x Current
17. What makes a circuit?
Electrical
device
Voltage source
Conductor Switch
converts
electrical energy
into another form
source of electricity,
such as batteries or
electric outlets
material that
allows current to
flow
controls the
current flow
18. Conductors vs Insulators
These materials allow
charges to flow freely.
These materials resist the
free movement of charges.
Conductors Insulators
silver
spoon
copper wire
rubber
balloon
rubber tire
diamond
19. Which of these circuits would work?
A B C
Circuit or Circus?
23. Circuit Components
Shown below are other circuit
components and their corresponding
electrical symbols:
battery closed switch open switch
resistor Variable Resistor
(Potentiometer)
fuse
30. What is
Inductor?
An inductor is a coil of wire through
which electrons move, and energy is
stored in the resulting magnetic field.
There are two fundamental principles of
electromagnetics:
1. Moving electrons create a magnetic
field.
2. Moving or changing magnetic fields
cause electrons to move. SI Unit: Henry(s)
Typical inductor values:1 Millihenry and Microhenry
31. The inductor:
Inductors are simply coils of wire.
• Can be air wound (just air in the
middle of the coil)
• Can be wound around a
permeable material (material
that concentrates magnetic
fields)
• Can be wound around a circular
form (toroid)
33. Diode
A diode is a semiconductor device that allows current to flow in
one direction while restricting it in the other
35. The Diode with AC Current
• If AC is applied to a diode:
a. During one half of the cycle, the
diode is forward biased and
current flows.
b. During the other half of the
cycle, the diode is reversed
biased, and the current stops.
• This is the process of rectification,
allowing current to flow in only one
direction.
• This is used to convert AC into
pulsating DC.
36. The
Transistor
How they work, an inside
look
• Basic types
a. NPN
b. PNP
• The basic transistor circuits
• Switch
• Amplifier
A transistor is a small semiconductor device that controls and amplifies electrical
signals, and can act as a switch or gate
