Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 7
Age: 15 years
Duration: 45 minutes
Subject: Basic Electricity
Curriculum Theme: Basic Electricity
Previous Lesson: Resistors: Components and Symbols.
Topic: RESISTOR COLOR CODING AND APPLICATION OF RESISTORS.
Subject Matter: Resistor colour code table, calculation of resistance using colour codes, determining colour bands for a given resistance value, uses of resistors in circuits.

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

State the resistor colour code table.
Calculate the resistance value of a resistor using its colour bands.
Determine the colour bands for a given resistance value.
List common applications of resistors in electrical circuits.

Affective Domain:

Appreciate the importance of resistor colour coding in electronics.
Show interest in identifying and using different types of resistors.

Psychomotor Domain:

Draw the standard resistor colour code table accurately.
Identify the colour bands on various resistors.

Participate actively in class discussions and problem-solving activities.
Collaborate with peers to solve resistor colour coding problems.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology (Junior Secondary School).
State Unified Scheme of Work for Basic Electricity SSS 1.
NERDC Basic Electricity for Senior Secondary Schools 1.
All About Circuits – Resistor Color Codes (for further resources).

Instructional Materials

The teacher will teach this lesson with the aid of:

Resistor colour code chart.
Assorted resistors (e.g., 4-band, 5-band).
Worksheets with resistor colour coding problems.
Marker and whiteboard.

Rationale for the Lesson

This lesson helps pupils understand how to identify the value of resistors, which are fundamental components in all electronic circuits. Knowing resistor colour codes enables pupils to correctly select and use resistors in practical applications, preventing damage to circuits and ensuring proper functionality.

Prerequisite/Previous Knowledge

Pupils are assumed to have prior knowledge of basic electrical components, including what a resistor is and its function in an electrical circuit.

Lesson Content/Board Summary

RESISTOR COLOUR CODING AND APPLICATION OF RESISTORS

1. Resistor Colour Code Table

The resistor colour code is a system used to indicate the resistance value and tolerance of a resistor using coloured bands. Each colour represents a specific numerical value, a multiplier, or a tolerance percentage.

The standard resistor colour code table is as follows:

Black – 0
Brown – 1
Red – 2
Orange – 3
Yellow – 4
Green – 5
Blue – 6
Violet – 7
Grey – 8
White – 9

Tolerance bands:

Gold – ±5%
Silver – ±10%
No Colour – ±20%

2. Calculating Resistance using Colour Codes (4-Band Resistor)

For a 4-band resistor, the bands are read from left to right:

First band: First digit of the resistance value.
Second band: Second digit of the resistance value.
Third band: Multiplier (power of 10).
Fourth band: Tolerance percentage.

Example: A resistor with bands Red, Yellow, Orange, Gold.

Red = 2 (first digit)
Yellow = 4 (second digit)
Orange = 3 (multiplier, 10^3)
Gold = ±5% (tolerance)

Resistance = 24 × 10^3 Ohms ±5% = 24,000 Ohms ±5% = 24 kOhms ±5%.

3. Determining Colour Bands for a Given Resistance Value

To determine the colour bands for a given resistance value, convert the value into the standard format (two digits multiplied by a power of 10), then match the digits and multiplier to their corresponding colours. The tolerance is usually specified or assumed.

Example: Determine the colour bands for a 330 kOhms ±5% resistor.

330 kOhms = 330,000 Ohms = 33 x 10^4 Ohms.
First digit ‘3’ = Orange.
Second digit ‘3’ = Orange.
Multiplier ’10^4′ = Yellow.
Tolerance ‘±5%’ = Gold.

Therefore, the colour bands are Orange, Orange, Yellow, Gold.

4. Uses of Resistors in Circuits

Resistors are important components in various electrical and electronic circuits. The following are common uses of resistors:

Limiting Current: Resistors are used to reduce the amount of current flowing through a circuit or a specific component, protecting sensitive devices.
Voltage Division: Two or more resistors can be connected in series to divide a voltage into smaller, specific levels.
Heat Generation: Resistors can convert electrical energy into heat, used in applications like heating elements.
Timing Circuits: In combination with capacitors, resistors create RC circuits used for timing delays.
Pull-up/Pull-down Resistors: Used in digital circuits to ensure a definite logic state for input pins.
Controlling LED Brightness: A series resistor limits the current to an LED, preventing it from burning out and controlling its brightness.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction/Questioning
Teacher’s Activity: The teacher greets the pupils and asks them to recall the previous lesson on resistors. The teacher then asks how they think the value of a resistor is identified since it is usually too small to print on. This leads to the topic of resistor colour coding.
Pupils’ Activity: Pupils respond to the questions and engage in a brief discussion, showing their previous knowledge and curiosity about the new topic.
Learning Point: Pupils recall prior knowledge and are introduced to the lesson’s topic.

Step 2: Presentation of Resistor Colour Code Table and its Use

Time: 15 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher displays a resistor colour code chart and explains each colour’s numerical value, multiplier, and tolerance. The teacher then demonstrates how to read a 4-band resistor, explaining the function of each band (first digit, second digit, multiplier, tolerance) with clear examples.
Pupils’ Activity: Pupils observe the chart, listen attentively, ask questions for clarification, and copy the colour code table into their notebooks.
Learning Point: Pupils understand the resistor colour code table and the method for calculating resistance from colour bands.

Step 3: Practice and Application

Time: 10 minutes
Teaching Skill: Guided Practice/Discussion
Teacher’s Activity: The teacher provides various examples of resistors with different colour bands and guides pupils through calculating their resistance values. The teacher also presents resistance values and guides pupils on how to determine the corresponding colour bands. Afterwards, the teacher facilitates a discussion on practical applications of resistors in everyday devices.
Pupils’ Activity: Pupils practice calculating resistance values and determining colour bands, participating in problem-solving. They also contribute to the discussion on resistor applications.
Learning Point: Pupils gain practical skills in applying the colour code and understand the functional importance of resistors.

Step 4: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

State the colour code for the number 5.
Calculate the resistance value of a resistor with the following colour bands: Brown, Black, Red, Gold.
What are the colour bands for a 56 kOhms ±5% resistor?
Mention two common uses of resistors in electrical circuits.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 5: Conclusion

Time: 5 minutes
Teaching Skill: Summarization/Assignment
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the importance of resistor colour coding and their applications. The teacher then assigns homework, which includes more practice problems on resistor colour coding.
Pupils’ Activity: Pupils listen to the summary and copy down the homework assignment.
Learning Point: Pupils consolidate their learning and are given tasks to reinforce their understanding.

Lesson Keywords

Resistor – An electrical component that limits or regulates the flow of electrical current in an electronic circuit.
Colour Code – A system using coloured bands to indicate the value and tolerance of a resistor.
Tolerance – The permissible variation of a resistor’s actual resistance from its nominal (marked) value, expressed as a percentage.
Multiplier – The factor by which the first two digits of a resistor’s value are multiplied.
Ohm – The SI unit of electrical resistance, represented by the symbol Ω.

Differentiation

For pupils who grasp the concept quickly, the teacher will provide more complex problems involving 5-band resistors or ask them to research specialized resistor types. For pupils requiring additional support, the teacher will provide simplified charts, one-on-one guidance, and repeat explanations with more visual aids and simpler examples.

Note for teachers using this lesson plan

Ensure that actual resistors are available for pupils to handle and observe the colour bands. Practical demonstration with a multimeter to measure the resistance of colour-coded resistors can significantly enhance understanding. Encourage pupils to use mnemonic devices to remember the colour code sequence.