Presentation for teaching electrical energy and circuits to middle schoolers

1. Electrical Energy
Electrical energy (or electricity) is
energy that exists as a result of charged
particles, such as electrons and ions.
When these charged particles move
through a conductor, electric current
is created.

2. Sources of Electrical Energy
• Like all forms of energy, electrical energy is gotten by the
conversion of another form of energy.
• Let us look at some of these sources:
– Wind
– Hydropower
– Nuclear power
AeFA Foundation - Electrical Energy

3. Current, Potential Difference and Resistance
• Electric current (I) refers to the flow of electricity through a
conductor, as a result of the flow of charged particles, e.g.
electrons.
– Current is measured in amperes (A), using an instrument called
an ammeter.
• Potential difference (V) is the work done to move charged
particles through a conductor.
– In an electric cell, the potential difference that “pumps” charged
particles through a conductor is known as the electromotive
force (emf).
– Potential difference is measured in volts (V), and is measured
using a voltmeter.
• Resistance (R) is the ability of a material to prevent the flow
of current (and electrical charges) through it.
– Resistance is measured in ohms (Ω).
conductor (wire)
potential
difference/
emf
electric
current
resistance
AeFA Foundation - Electrical Energy

4. Ohm’s Law
• This is a physical law that shows the relationship between
potential difference (V), electric current (I) and resistance (R).
• Ohm’s law states that “the potential difference (V) across a
conductor is directly proportional to the current (I) flowing
through that conductor, at constant temperature.”
V x= RI
RR
AeFA Foundation - Electrical Energy

5. Examples
• A battery generates a current of 4A in an electric circuit with a
resistance of 3Ω. What is the emf of the battery?
Solution
V = IR
V = 4A x 3Ω
V = 12V
• A 9V battery generates a current of 4.5A in an
electric circuit. What is the resistance of the
circuit?
Solution
V = IR
R =
I
V
R = 9V
4.5A
= 2Ω
AeFA Foundation - Electrical Energy

6. Electrical Circuits
• An electrical circuit is a complete path through which electric
current passes.
• It consists of a source of voltage or emf (usually a battery), a
conductor (usually a copper wire) and a load (something that
uses up the electric current).
AeFA Foundation - Electrical Energy

7. Components of an Electrical Circuit
• Cell (or battery)
– Converts chemical energy into electric energy.
– It is one of the most common sources of emf in a
circuit.
– A battery is a collection of more than one cell.
• Light bulb:
– Converts electric energy carried by the current into
light energy.
– It is the most common type of load used in simple
electric circuits.
dry cellbattery battery
AeFA Foundation - Electrical Energy

8. resistors
Components of an Electric Circuit
• Resistor:
– Controls the amount of electric current that passes through the
circuit.
– It is usually made of a conductor with a known resistance.
• Switch:
– It closes to allow electric current pass through the circuit, and opens
to stop electric current from passing through.OR
variable resistor
open switch closed switch
AeFA Foundation - Electrical Energy

9. Types of Electrical Circuits
• There are two main kinds of electrical circuit connections:
– Series connection:
In series connection, one component is connected directly to one another in
sequence.
– Parallel connection:
In parallel connection, components are connected to common points, rather
than directly to one another.
dry cells bulb
resistor
battery
bulb
resistor
AeFA Foundation - Electrical Energy

10. Comparing Series and Parallel Circuits
Series
• The components are connected
directly to each other.
• The current through the components
are equal, but the voltages through
them are different.
• A faulty component breaks the circuit
Parallel
• The components are connected to a
common point, rather than directly to
each other
• The current through the components
are different, but the voltage through
them are equal.
• The circuit remains intact if only one
component is faulty
AeFA Foundation - Electrical Energy