Electrical energy exists as a result of charged particles like electrons moving through a conductor, creating an electric current. It can be generated from various sources by converting other forms of energy, such as wind, hydropower, and nuclear power. In an electrical circuit, current is produced by a potential difference or electromotive force from a source like a battery, and flows through a conductor. Resistance opposes the flow of current, and is measured using Ohm's law, which relates potential difference, current, and resistance in a circuit.

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