The ohms law

1. ELECTRICITY
THE ELECTRIC CIRCUIT

2. INTRODUCTION
Electrical circuits are essential to understand the technology that
uses electrical power in the real world context. We depend on
the use of electricity and electrical appliances to make many
things possible in our daily lives around different sociocultural
contexts, for example it becomes clear when there is a power
failure and we cannot use the kettle to heat up the water or boil
the water.

3. THE OHMS LAW
There are three fundamental components of the electric circuits
which include current, voltage ( potential difference) and
resistance.
• Electric circuit (I) – is the rate of flow of charge through a
circuit.
• Potential difference or voltage (V) – the amount of energy per
unit charge between two points in a circuit.
• Resistance ( R) – measure of how difficult or hard to push the
current through a circuit element.

4. THE OHM’S LAW
Georg Simon Ohm discovered the important
relationship between the current, voltage and
resistance which is called the Ohm’s law.
The definition of Ohm’s law:
The amount of Electric Current through a metal
conductor at a constant temperature in a electric
circuitis proportional To the voltage a cross the
conductor and can be described by I=V/R where I
is the current through the conductor, V is the
voltage across the conductor and R is the
resistance of the conductor.
Inother words, at constant Temperature, the
resistance of the conductor is constant
,independent of the voltage applied across it or
current passed through it.

5. THE GRAPH
INTERPRETATION OF THE
OHM’S LAW
OHM’S LAW TELLS US THAT IF A CONDUCTOR IS AT A CONSTANT
TEMPERATURE, THE CURRENT FLOWING THROUGH THE
CONDUCTOR IS DIRECTLY PROPORTIONAL TO THE VOLTAGE
ACROSS IT. THIS MEANS THAT IF WE PLOT VOLTAGE ON THE X-AXIS
OF A GRAPH AND CURRENT ON THE Y-AXIS OF THE GRAPH,WE WILL
GET A STRAIGHT-LINE.

6. THE GRAPH OF CURRENT (I) VS. VOLTAGE
(V)

7. OHMIC AND NON-OHMIC CONDUCTORS
Ohmic conductors are the conductors that follow the ohm’s law
which means that their resistance does not change with changing
current and voltage.
Non-ohmic conductors are those that conductors do not follow
the ohm’s la which means that their resistance changes with
changing current and voltage.

8. EXAMPLE 1
The circuit diagram below is shown:

9. IF THE RESISTANCE IN THE RESISTOR IS 10 OHMS
AND THE CURRENT THROUGH IT IS 4A. WHAT IS
THE POTENTIAL DIFFERENCE OR VOLTAGE
ACROSS THE RESISTOR?

10. SOLUTION:
Applying the Ohms law:
R=V/I
This implies that V= I × V
= (4A) × (10ohms)
= 40 V

11. IN CONCLUSION
The electric circuits are built to make electricity useful in a real
world context which makes it a most essential component in
transformation of technological innovation.

12. RESOURCES
• Siyavula CAPS Physical Sciences Grade 11.
• Platinum Grade 11 Physical Sciences.