This slides will help learners get a better understanding of what ER(Electrical Resistance) is and how it works.

1. ELECTRICAL RESISTANCE
COMPILED BY MR MOUTSHE P.I
GRADE 9 2023.

2. LESSON
OBJECTIVES
1. The end of the lesson learners should be
able to:
➢ Define and explain resistance.
➢ List and discuss factors that affect
resistance.
➢ Demonstrate functions of a resistor in an
electrical circuit.
➢ Investigate the effect of length and
thickness of a conductor.
➢ Understand the importance value brought
by resistance/resistor in a circuit diagram.

3. RESISTOR
AND RESISTANCE
❑ Resistance- Is the measure of
opposition in the flow of current.
➢ NEW TERM: CURRENT, what do you
think current is?(brainstom>)
➢ Resistor- A component or device
having resistance to the passage of
electrical current.
This Photo by Unknown Author is licensed under CC BY-NC

4. RESISTANCE
• Copper wire has very little resistance
• Symbols used for resistor and wire
Resistor →
Wire →

5. FACTORS AFFECTING
RESISTANCE
➢ The type of material which the resistor is
made- certain materials resist the flow of
electric current more or less than other
materials do.
➢ The length of the resistor- when the
length of a conductor is increased, its
resistance also increases.
➢ The thickness of the resistor- Thicker
wires allow more electric charges to flow
than thinner wires.
➢ The temperature of the conductor-
increasing the temperature (typically)
increases resistance.

6. Resistance
➢ The resistance varies directly(both
increase/decrease with the same factor) with
length and inversely(one increase by a factor the
other will decrease by the same factor of
increment) with width (or cross-sectional area) of
a wire
➢ For example, trying to get a lot of water through
thick/thin pipe.
✓ Short, thick wire → small resistance
✓ Long, skinny wire → large resistance

7. NAME ANY FACTOR AFFECTING
RESISTANCE AND HOW IT
AFFECTS IT IN A CIRCUIT ?
.

8. DEMONSTRATIONS OF
RESISTOR FUNCTIONS.
❖NB- Bear in mind that a light bulb is
also a resistor.

9. IMPORTANCDE AND
USES OF A RESISTOR IN
AN ELECTRIC CIRCUIT.
1. USES
✓ A resistor controls the flow of the electrical
current within a circuit.
✓ A resistor can be used to transfer electrical
energy into light (light bulb) or into heat (kettle
element).
2. IMPORTANCE
✓ To avoid permanent damage to components and
ensure safety, limiting the current flowing through
a component or load in electronic circuits is
crucial. Excessive current can cause overheating of
the component and lead to failures in other circuit
components, posing a potential safety hazard.