Thin Lenses

Types of Lenses and Effects on Light
Definition of Terms and Ray Diagrams

By the end of the lesson, the learner should be able to:
Define a lens and distinguish between convex and concave lenses; Describe the effect of lenses on parallel rays of light; Explain convergence and divergence of light rays; Identify practical examples of different lens types

Q/A on refraction concepts; Experiment 1.1 - investigating effects of lenses on parallel rays using sunlight and ray box; Demonstration of convergence and divergence; Group identification of lens types in everyday objects; Drawing and analysis of ray diagrams

Ray box; Various convex and concave lenses; White screen; Plane mirror; Card with parallel slits; Sunlight or strong lamp
Various lenses; Rulers; Graph paper; Ray boxes; Charts showing lens terminology; Drawing materials; Laser pointers (if available)

KLB Secondary Physics Form 4, Pages 1-6

Thin Lenses

Image Formation by Converging Lenses
Image Formation by Diverging Lenses and Linear Magnification

By the end of the lesson, the learner should be able to:
Locate images for different object positions using ray diagrams; Describe image characteristics (real/virtual, erect/inverted, magnified/diminished); Explain applications in telescope, camera, projector and magnifying glass; Understand relationship between object position and image properties

Review of ray construction rules; Systematic ray diagram construction for objects at infinity, beyond 2F, at 2F, between F and 2F, at F, and between F and lens; Analysis of image characteristics for each position; Discussion of practical applications; Demonstration using lens, object and screen

Converging lenses; Objects; White screen; Metre rule; Candle; Graph paper; Charts showing applications; Camera (if available)
Diverging lenses; Graph paper; Rulers; Calculators; Examples from textbook; Objects of known heights; Measuring equipment

KLB Secondary Physics Form 4, Pages 8-12

Thin Lenses

The Lens Formula
Determination of Focal Length I
Determination of Focal Length II

By the end of the lesson, the learner should be able to:
Derive the lens formula using similar triangles; Understand and apply the Real-is-positive sign convention; Use the lens formula to solve problems involving object distance, image distance and focal length; Solve Examples 4, 5, 6, and 7 from textbook
Estimate focal length using distant objects (Experiment 1.2); Determine focal length using plane mirror method (Experiment 1.3); Explain the principle behind each method; Measure focal length accurately and identify sources of error

Review of magnification concepts; Mathematical derivation of lens formula from similar triangles; Introduction to sign convention rules; Step-by-step solution of Examples 4-7; Practice problems applying lens formula to various situations; Group work on formula applications
Q/A on focal length concept; Practical performance of Experiment 1.2 - distant object method; Demonstration and practice of Experiment 1.3 - plane mirror method (both no-parallax and illuminated object methods); Recording and analysis of results; Discussion of accuracy and error sources

Mathematical instruments; Charts showing derivation; Calculators; Worked examples; Sign convention chart; Practice worksheets
Converging lenses; Lens holders; Metre rule; White screen; Distant objects; Plane mirror; Pins; Cork; Glass rod; Light source; Cardboard with cross-wires
Experimental setup materials; Graph paper; Calculators; Data tables; Examples 8-10 from textbook; Materials for displacement method

KLB Secondary Physics Form 4, Pages 14-20
KLB Secondary Physics Form 4, Pages 16-19

Thin Lenses

Power of Lens and Simple Microscope

By the end of the lesson, the learner should be able to:
Define power of a lens and calculate using P = 1/f; Use dioptre as unit and distinguish positive/negative power; Explain working of simple microscope (magnifying glass); Understand why short focal length lenses are preferred; Calculate magnification of simple microscope

Q/A on focal length concepts; Introduction to lens power with practical examples; Power calculations and comparisons; Demonstration of simple microscope setup; Analysis of magnification factors; Discussion of applications and limitations of magnifying glass

Various lenses of different focal lengths; Magnifying glasses; Small objects; Calculators; Power calculation charts; Small print materials; Biological specimens

KLB Secondary Physics Form 4, Pages 26-28

Thin Lenses

Compound Microscope

By the end of the lesson, the learner should be able to:
Describe structure and working of compound microscope; Explain functions of objective lens and eyepiece; Calculate total magnification; Solve Example 11 involving lens separation; Understand normal adjustment of compound microscope

Review of simple microscope; Introduction to compound microscope structure; Ray tracing through objective and eyepiece; Mathematical analysis of total magnification; Step-by-step solution of Example 11; Practical demonstration with microscope parts

Compound microscope; Charts showing microscope structure; Lenses representing objective and eyepiece; Calculators; Example 11 from textbook; Ray tracing materials

KLB Secondary Physics Form 4, Pages 28-30

Thin Lenses

The Human Eye

By the end of the lesson, the learner should be able to:
Describe structure of human eye and functions of each part; Explain accommodation process and role of ciliary muscles; Define near point and far point; Understand how eye focuses at different distances; Compare eye structure with camera

Introduction to human eye as natural optical instrument; Detailed study of eye structure using charts/models; Demonstration of accommodation using flexible lens model; Practical measurement of near and far points; Comparison table of eye vs camera similarities and differences

Charts/models of human eye; Torch for demonstrations; Eye model with flexible lens; Objects at various distances; Measuring equipment; Camera comparison charts

KLB Secondary Physics Form 4, Pages 30-32

Thin Lenses

Defects of Vision
The Camera and Applications Review

By the end of the lesson, the learner should be able to:
Describe short sight (myopia) and its causes; Explain correction of myopia using diverging lenses; Describe long sight (hypermetropia) and its causes; Explain correction of hypermetropia using converging lenses; Draw ray diagrams showing defects and their corrections
Describe camera structure and working principles; Explain functions of camera lens, shutter, aperture, and film; Compare camera with human eye highlighting similarities and differences; Review all applications of lenses in optical instruments

Q/A on normal vision and accommodation; Analysis of myopia - causes, effects, and correction; Ray diagrams for uncorrected and corrected myopia; Study of hypermetropia - causes, effects, and correction; Ray diagrams for uncorrected and corrected hypermetropia; Demonstration using appropriate lenses
Review of optical instruments studied; Analysis of camera components and their functions; Detailed comparison of camera and eye; Discussion of focusing mechanisms; Comprehensive review of lens applications in telescope, microscope, camera, spectacles, and magnifying glass

Charts showing vision defects; Converging and diverging lenses; Eye models; Spectacles with different lenses; Vision test materials; Ray diagram materials
Camera (if available); Charts showing camera structure; Comparison tables; Review charts of all applications; Summary materials; Demonstration equipment

KLB Secondary Physics Form 4, Pages 32-33
KLB Secondary Physics Form 4, Pages 33-35

Electromagnetic Spectrum

Introduction and Properties of Electromagnetic Waves

By the end of the lesson, the learner should be able to:
Define electromagnetic waves and identify their nature; State properties common to all electromagnetic waves; Arrange electromagnetic radiations in order of wavelength and frequency; Calculate wave properties using c = fλ; Solve Examples 1 and 2 from textbook

Q/A on wave concepts from previous studies; Introduction to electromagnetic waves using everyday examples; Study of electromagnetic spectrum chart; Discussion of wave properties (speed, frequency, wavelength); Mathematical relationship between wave parameters; Solution of Examples 1 and 2 involving calculations

Electromagnetic spectrum charts; Wave demonstration materials; Calculators; Radio; Mobile phone; Examples from textbook; Charts showing wave properties

KLB Secondary Physics Form 4, Pages 79-81

Electromagnetic Spectrum

Production and Detection of Electromagnetic Waves I

By the end of the lesson, the learner should be able to:
Explain production of gamma rays, X-rays, and ultraviolet radiation; Describe detection methods for high-energy radiations; Understand energy transitions in atoms and nuclei; Relate wave energy to frequency using E = hf; Solve Example 3 involving X-ray calculations

Review of electromagnetic properties through Q/A; Study of high-energy radiation production mechanisms; Analysis of detection methods (photographic plates, G-M tubes, fluorescent materials); Discussion of atomic and nuclear energy changes; Step-by-step solution of Example 3; Safety considerations for high-energy radiations

Charts showing radiation production; Photographic film; Fluorescent materials; UV lamp (if available); Geiger counter (if available); Example 3 materials; Safety equipment demonstrations

KLB Secondary Physics Form 4, Pages 81-82

Electromagnetic Spectrum

Production and Detection of Electromagnetic Waves I

By the end of the lesson, the learner should be able to:
Explain production of gamma rays, X-rays, and ultraviolet radiation; Describe detection methods for high-energy radiations; Understand energy transitions in atoms and nuclei; Relate wave energy to frequency using E = hf; Solve Example 3 involving X-ray calculations

Review of electromagnetic properties through Q/A; Study of high-energy radiation production mechanisms; Analysis of detection methods (photographic plates, G-M tubes, fluorescent materials); Discussion of atomic and nuclear energy changes; Step-by-step solution of Example 3; Safety considerations for high-energy radiations

Charts showing radiation production; Photographic film; Fluorescent materials; UV lamp (if available); Geiger counter (if available); Example 3 materials; Safety equipment demonstrations

KLB Secondary Physics Form 4, Pages 81-82

Electromagnetic Spectrum

Production and Detection of Electromagnetic Waves II
Applications of Electromagnetic Waves I

By the end of the lesson, the learner should be able to:
Explain production of visible light, infrared, microwaves, and radio waves; Describe detection methods for each radiation type; Understand role of oscillating circuits in radio wave production; Compare detection mechanisms across the spectrum; Demonstrate detection of some radiations
Describe medical applications of gamma rays and X-rays; Explain industrial uses of high-energy radiations; Understand applications in sterilization and cancer therapy; Discuss X-ray photography and crystallography; Analyze benefits and limitations of high-energy radiation applications

Q/A on high-energy radiations; Study of lower-energy radiation production (thermal, electronic oscillations); Analysis of detection methods (eyes, thermopiles, crystal detectors, radio receivers); Practical demonstrations of infrared detection; Discussion of antenna and oscillating circuit principles; Group identification of sources and detectors
Review of radiation properties and production; Detailed study of gamma ray applications (sterilization, cancer treatment, flaw detection); Analysis of X-ray applications (medical photography, security, crystallography); Discussion of controlled radiation exposure; Examination of X-ray photographs and medical applications

Infrared sources (heaters); Thermometer with blackened bulb; Radio receivers; Microwave oven (demonstration); Oscillating circuit models; Various electromagnetic sources
X-ray photographs; Medical imaging examples; Industrial radiography charts; Cancer treatment information; Sterilization process diagrams; Safety protocol charts

KLB Secondary Physics Form 4, Pages 81-82
KLB Secondary Physics Form 4, Pages 82-84

Electromagnetic Spectrum

Applications of Electromagnetic Waves II

By the end of the lesson, the learner should be able to:
Explain applications of ultraviolet radiation; Describe uses of visible light in technology; Understand infrared applications in heating and imaging; Analyze microwave applications in cooking and radar; Discuss radio wave applications in communication

Q/A on high-energy radiation applications; Study of UV applications (fluorescence, sterilization, vitamin D, forgery detection); Analysis of visible light uses (photography, optical fibers, lasers); Exploration of infrared applications (heating, night vision, remote controls); Discussion of microwave and radio wave technologies

UV lamp demonstrations; Optical fiber samples; Infrared thermometer; Microwave oven (demonstration); Radio equipment; Remote controls; Radar images; Communication devices

KLB Secondary Physics Form 4, Pages 82-85

Electromagnetic Spectrum

Specific Applications - Radar and Microwave Cooking

By the end of the lesson, the learner should be able to:
Explain principles of radar (radio detection and ranging); Describe microwave oven operation and safety features; Understand reflection and detection in radar systems; Explain how microwaves heat food molecules; Apply wave principles to practical technologies

Review of microwave and radio wave properties; Detailed analysis of radar operation and applications; Study of microwave oven components (magnetron, stirrer, safety features); Discussion of wave reflection and detection principles; Analysis of molecular heating mechanisms; Safety considerations and precautions

Radar system diagrams; Microwave oven cross-section charts; Wave reflection demonstrations; Safety instruction materials; Magnetron information; Aircraft/ship tracking examples

KLB Secondary Physics Form 4, Pages 84-85

Electromagnetic Spectrum

Specific Applications - Radar and Microwave Cooking

By the end of the lesson, the learner should be able to:
Explain principles of radar (radio detection and ranging); Describe microwave oven operation and safety features; Understand reflection and detection in radar systems; Explain how microwaves heat food molecules; Apply wave principles to practical technologies

Review of microwave and radio wave properties; Detailed analysis of radar operation and applications; Study of microwave oven components (magnetron, stirrer, safety features); Discussion of wave reflection and detection principles; Analysis of molecular heating mechanisms; Safety considerations and precautions

Radar system diagrams; Microwave oven cross-section charts; Wave reflection demonstrations; Safety instruction materials; Magnetron information; Aircraft/ship tracking examples

KLB Secondary Physics Form 4, Pages 84-85

Electromagnetic Spectrum
Electromagnetic Induction

Hazards and Safety Considerations
Introduction and Historical Background

By the end of the lesson, the learner should be able to:
Identify hazards of high-energy electromagnetic radiations; Explain biological effects of UV, X-rays, and gamma rays; Describe safety measures for radiation protection; Understand delayed effects like cancer and genetic damage; Apply safety principles in radiation use
Define electromagnetic induction and its significance; Explain Faraday's discovery and its impact on modern technology; Understand the relationship between magnetism and electricity; Identify examples of electromagnetic induction in daily life; Appreciate the importance of relative motion in electromagnetic phenomena

Q/A on electromagnetic applications; Study of radiation hazards and biological effects; Analysis of skin damage, cell destruction, and genetic effects; Discussion of Chernobyl disaster and radiation accidents; Exploration of safety measures (shielding, distance, time limits); Application of ALARA principle (As Low As Reasonably Achievable)
Q/A on magnetic fields and electric current relationships from previous studies; Introduction to Michael Faraday's discovery and its historical significance; Discussion of electromagnetic induction examples in daily life (generators, transformers, motors); Overview of chapter content and learning objectives; Introduction to practical applications in power generation and electronics

Radiation hazard charts; Safety equipment demonstrations; Chernobyl disaster information; Biological effect diagrams; Safety protocol materials; Radiation protection examples
Charts showing Faraday's experiments; Pictures of power stations; Transformers; Generators; Historical timeline of electromagnetic discoveries; Real-world applications display

KLB Secondary Physics Form 4, Pages 85
KLB Secondary Physics Form 4, Pages 86

Electromagnetic Induction

Conditions for Electromagnetic Induction - Straight Conductor

By the end of the lesson, the learner should be able to:
Perform Experiment 5.1 using straight conductor; Identify conditions necessary for inducing e.m.f. in a straight conductor; Observe effects of different types of motion on induced current; Understand the importance of relative motion between conductor and magnetic field; Analyze galvanometer deflections

Performance of Experiment 5.1 using straight conductor AB in U-shaped magnet; Systematic investigation of conductor movement (vertical up/down, parallel to field, stationary, different angles); Observation and recording of galvanometer deflections; Analysis of current direction changes with motion reversal; Discussion of relative motion importance and field cutting concept

Thick electric conductor; U-shaped magnet; Galvanometer; Connecting wires; Clamp and stand setup; Data recording sheets

KLB Secondary Physics Form 4, Pages 86-87

Electromagnetic Induction

Conditions for Electromagnetic Induction - Coils

By the end of the lesson, the learner should be able to:
Perform Experiment 5.1 using coils; Compare induction effects in straight conductors vs coils; Observe effects of magnet movement into and out of coils; Understand flux linkage concept; Analyze why coils are more effective than single conductors

Continuation of Experiment 5.1 using coil instead of straight conductor; Investigation of magnet movement into coil, out of coil, and stationary positions; Comparison of deflection magnitudes between straight conductor and coil setups; Analysis of why coils produce larger induced e.m.f.; Discussion of magnetic flux and flux linkage concepts

Coils of different sizes; Magnets of various strengths; Galvanometer; Connecting wires; Comparison data sheets

KLB Secondary Physics Form 4, Pages 87-88

Electromagnetic Induction

Conditions for Electromagnetic Induction - Coils

By the end of the lesson, the learner should be able to:
Perform Experiment 5.1 using coils; Compare induction effects in straight conductors vs coils; Observe effects of magnet movement into and out of coils; Understand flux linkage concept; Analyze why coils are more effective than single conductors

Continuation of Experiment 5.1 using coil instead of straight conductor; Investigation of magnet movement into coil, out of coil, and stationary positions; Comparison of deflection magnitudes between straight conductor and coil setups; Analysis of why coils produce larger induced e.m.f.; Discussion of magnetic flux and flux linkage concepts

Coils of different sizes; Magnets of various strengths; Galvanometer; Connecting wires; Comparison data sheets

KLB Secondary Physics Form 4, Pages 87-88

Electromagnetic Induction

Factors Affecting Induced E.M.F. - Rate of Change
Factors Affecting Induced E.M.F. - Magnetic Field Strength

By the end of the lesson, the learner should be able to:
Perform Experiment 5.2 investigating rate of change effects; Understand relationship between speed of motion and induced e.m.f.; Collect and analyze data on rate of flux change; Establish that faster changes produce larger e.m.f.; Apply findings to practical situations
Perform Experiment 5.3 investigating magnetic field strength effects; Understand relationship between field strength and induced e.m.f.; Control variables in electromagnetic experiments; Use electromagnets to vary field strength; Apply experimental findings to solve problems

Performance of Experiment 5.2 investigating relationship between rate of change of magnetic flux and induced e.m.f.; Systematic variation of magnet withdrawal speeds (very fast, moderate, very slow); Recording and comparison of galvanometer deflections; Data analysis and conclusion drawing; Discussion of practical implications in generators and other applications
Performance of Experiment 5.3 investigating relationship between magnetic field strength and induced e.m.f.; Setup of electromagnet with variable current control; Investigation of wire PQ movement in different field strengths; Recording galvanometer deflections for different electromagnet currents; Analysis of results and relationship establishment

Coil of at least 50 turns; Sensitive galvanometer; Magnet; Stopwatch; Data collection tables; Graph paper for analysis
U-shaped electromagnet; Variable resistor; Wire PQ; Galvanometer; Ammeter; Connecting wires; Power supply; Data recording materials

KLB Secondary Physics Form 4, Pages 88-89
KLB Secondary Physics Form 4, Pages 89

Electromagnetic Induction

Factors Affecting Induced E.M.F. - Number of Turns

By the end of the lesson, the learner should be able to:
Perform Experiment 5.4 investigating effect of coil turns; Understand relationship between number of turns and induced e.m.f.; Construct coils with different numbers of turns; Analyze why more turns produce larger e.m.f.; State Faraday's law of electromagnetic induction

Performance of Experiment 5.4 investigating relationship between number of turns and induced e.m.f.; Construction of solenoids with 60, 50, 40, 30, and 20 turns; Systematic testing with same magnet withdrawal speed; Recording and analysis of galvanometer readings; Mathematical relationship establishment; Statement of Faraday's law based on experimental evidence

Insulated copper wire; Sensitive galvanometer; Magnet; Connecting wires; Wire cutting and measuring tools; Data analysis sheets

KLB Secondary Physics Form 4, Pages 89-90

Electromagnetic Induction

Lenz's Law and Direction of Induced Current

By the end of the lesson, the learner should be able to:
Perform Experiment 5.5 determining direction of induced current; State Lenz's law and explain its significance; Understand energy conservation in electromagnetic induction; Predict current direction using Lenz's law; Relate Lenz's law to conservation of energy principle

Performance of Experiment 5.5(a) establishing galvanometer deflection direction; Performance of Experiment 5.5(b) investigating induced current direction with magnet movement; Analysis of current directions and magnetic pole formation; Statement and explanation of Lenz's law; Discussion of energy conservation and opposition principle; Practice in predicting current directions

Variable resistor; Sensitive center-zero galvanometer; Connecting wires; Coil; Magnet; Switch; Battery; Direction analysis charts

KLB Secondary Physics Form 4, Pages 90-93

Electromagnetic Induction

Fleming's Right-Hand Rule

By the end of the lesson, the learner should be able to:
Perform Experiment 5.6 with straight conductors; State Fleming's right-hand rule (dynamo rule); Apply the rule to determine direction of induced current; Understand relationship between motion, field, and current directions; Solve Example 1 involving square loop movement

Performance of Experiment 5.6 determining induced current direction in straight conductor; Introduction and demonstration of Fleming's right-hand rule; Practice applying the rule to various conductor movements; Step-by-step solution of Example 1 (square loop in magnetic field); Analysis of current directions in different parts of the loop; Verification of Fleming's rule consistency with Lenz's law

U-shaped magnet; Thick wire AB; Marked center-zero galvanometer; Hand models for rule demonstration; Example 1 setup materials; Direction analysis worksheets

KLB Secondary Physics Form 4, Pages 93-97

Electromagnetic Induction

Fleming's Right-Hand Rule
Applications of Induction Laws

By the end of the lesson, the learner should be able to:
Perform Experiment 5.6 with straight conductors; State Fleming's right-hand rule (dynamo rule); Apply the rule to determine direction of induced current; Understand relationship between motion, field, and current directions; Solve Example 1 involving square loop movement
Solve Examples 2 and 3 involving current direction; Apply Lenz's law to predict current directions in circuits; Understand induced current effects in neighboring circuits; Analyze changing magnetic fields and their effects; Use both Fleming's rule and Lenz's law in problem solving

Performance of Experiment 5.6 determining induced current direction in straight conductor; Introduction and demonstration of Fleming's right-hand rule; Practice applying the rule to various conductor movements; Step-by-step solution of Example 1 (square loop in magnetic field); Analysis of current directions in different parts of the loop; Verification of Fleming's rule consistency with Lenz's law
Q/A review of Fleming's rule and Lenz's law; Step-by-step solution of Example 2 (current in conductor AB affecting nearby loop); Detailed analysis of Example 3 (magnet movement and coil current direction); Practice problems involving current direction prediction; Group work on applying both laws to various scenarios; Discussion of consistency between different methods

U-shaped magnet; Thick wire AB; Marked center-zero galvanometer; Hand models for rule demonstration; Example 1 setup materials; Direction analysis worksheets
Examples 2 and 3 setup materials; Problem-solving worksheets; Charts showing current direction analysis; Group work materials; Calculators

KLB Secondary Physics Form 4, Pages 93-97
KLB Secondary Physics Form 4, Pages 94-97

Electromagnetic Induction

Mutual Induction

By the end of the lesson, the learner should be able to:
Define mutual induction and demonstrate its occurrence; Perform Experiment 5.7 showing mutual induction between coils; Explain factors affecting mutual induction; Understand primary and secondary coil relationships; Discuss enhancement methods using iron cores

Q/A on electromagnetic induction principles; Introduction to mutual induction concept and definition; Performance of Experiment 5.7 demonstrating mutual induction between primary and secondary coils; Investigation of switching effects, current changes, and A.C. source effects; Analysis of mutual induction enhancement using soft iron rod and ring; Discussion of applications in transformers

Two coils P and S; Galvanometer; Battery; A.C. power source; Switch; Rheostat; Connecting wires; Soft iron rod; Soft iron ring; Enhancement demonstration materials

KLB Secondary Physics Form 4, Pages 97-100

Electromagnetic Induction

Transformers - Basic Principles

By the end of the lesson, the learner should be able to:
Describe transformer structure and components; Explain working principle based on mutual induction; Perform Experiment 5.10 investigating secondary e.m.f. variation; Understand primary and secondary coil functions; Distinguish between step-up and step-down transformers

Review of mutual induction through Q/A; Introduction to transformer structure (primary coil, secondary coil, iron core); Performance of Experiment 5.10 - variation of secondary e.m.f. with number of turns; Observation of bulb brightness changes with turn variations; Analysis of step-up vs step-down transformer characteristics; Introduction to transformer symbols and representations

Long insulated copper wire; Soft iron rod; Low frequency A.C. source; A.C. voltmeter; Switch; Bulb; Transformer construction materials; Symbol charts

KLB Secondary Physics Form 4, Pages 100-102

Electromagnetic Induction

Transformer Equations and Calculations

By the end of the lesson, the learner should be able to:
Derive transformer turns rule equation; Apply transformer equations for voltage and current relationships; Calculate transformer efficiency; Solve Examples 4 and 5 involving transformer problems; Understand ideal vs practical transformer differences

Q/A on transformer working principles; Mathematical derivation of turns rule (Vp/Vs = Np/Ns); Development of current relationship (IpVp = IsVs for ideal transformer); Introduction to efficiency calculations; Step-by-step solution of Examples 4 and 5; Discussion of ideal transformer assumptions vs practical limitations

Calculators; Examples 4 and 5 materials; Mathematical derivation charts; Efficiency calculation worksheets; Transformer specification data

KLB Secondary Physics Form 4, Pages 102-105

Electromagnetic Induction

Transformer Equations and Calculations
Transformer Energy Losses and Example 6

By the end of the lesson, the learner should be able to:
Derive transformer turns rule equation; Apply transformer equations for voltage and current relationships; Calculate transformer efficiency; Solve Examples 4 and 5 involving transformer problems; Understand ideal vs practical transformer differences
Identify four main energy losses in transformers; Explain methods to minimize each type of energy loss; Understand lamination and its purpose; Solve Example 6 involving power transmission system; Calculate efficiency and power losses in practical systems

Q/A on transformer working principles; Mathematical derivation of turns rule (Vp/Vs = Np/Ns); Development of current relationship (IpVp = IsVs for ideal transformer); Introduction to efficiency calculations; Step-by-step solution of Examples 4 and 5; Discussion of ideal transformer assumptions vs practical limitations
Review of ideal transformer equations; Analysis of energy losses (flux leakage, copper losses, eddy currents, hysteresis loss); Study of loss minimization techniques including core lamination; Discussion of practical transformer efficiency; Step-by-step solution of Example 6 (complex power transmission system); Analysis of step-up and step-down transformer roles

Calculators; Examples 4 and 5 materials; Mathematical derivation charts; Efficiency calculation worksheets; Transformer specification data
Charts showing energy losses; Laminated core samples; Example 6 complex setup; Power transmission diagrams; Efficiency calculation materials; Loss minimization demonstration aids

KLB Secondary Physics Form 4, Pages 102-105
KLB Secondary Physics Form 4, Pages 105-108

Electromagnetic Induction

Applications - Generators, Microphones, and Induction Coils

By the end of the lesson, the learner should be able to:
Explain structure and working of A.C. and D.C. generators; Describe moving-coil microphone operation; Understand induction coil structure and applications; Compare slip rings with split ring commutators; Analyze generator output waveforms and applications

Review of electromagnetic induction in rotating systems; Detailed study of A.C. generator structure and sinusoidal output; Analysis of D.C. generator with split ring commutator; Explanation of moving-coil microphone components and sound conversion; Description of induction coil operation and high voltage generation; Discussion of applications in car ignition systems

A.C. generator model; D.C. generator model; Moving-coil microphone demonstration; Induction coil setup; Output waveform charts; Slip ring and commutator comparisons; Bicycle dynamo

KLB Secondary Physics Form 4, Pages 108-112

Mains Electricity

Sources of Mains Electricity
The Grid System and Power Transmission

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

State the main sources of mains electricity
Explain how different sources generate electrical energy
Compare advantages and disadvantages of different power sources
Describe the environmental impact of various power sources

Prior knowledge review on electrical energy
Discussion on local power sources in Kenya
Field trip planning to nearby power station
Group presentations on different power sources
Q&A session on power generation methods

Pictures of power stations
Charts showing different energy sources
Videos of power generation
Maps of Kenya's power grid
Sample coal, biomass materials
Chart of national grid system
Transmission line models
Maps showing power lines
Transformer models
Voltage measurement devices

KLB Secondary Physics Form 4, Pages 117

Mains Electricity

High Voltage Transmission and Power Losses

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

Explain why power is transmitted at high voltage
Calculate power losses in transmission
State dangers of high voltage transmission
Apply the formula P = I²R to transmission problems

Review of Ohm's law and power formulas
Demonstration of power loss calculations
Worked examples on transmission efficiency
Discussion on safety measures for transmission lines
Group problem-solving activities

Calculators
Worked example sheets
Pictures of transmission towers
Safety warning signs
Formula charts

KLB Secondary Physics Form 4, Pages 118-121

Mains Electricity

Domestic Wiring System
Fuses, Circuit Breakers and Safety Devices
Ring Mains Circuit and Three-Pin Plugs
Electrical Energy Consumption and Costing

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

Describe the domestic wiring system
Identify components of consumer fuse box
Explain the function of live, neutral and earth wires
Draw simple domestic wiring circuits

Describe the ring mains circuit
Explain advantages of ring mains system
Wire a three-pin plug correctly
Identify wire color coding in electrical systems

Q&A on transmission systems
Examination of house wiring components
Drawing domestic wiring diagrams
Identification of electrical safety features
Practical observation of electrical installations
Q&A on fuses and safety devices
Drawing ring mains circuit diagrams
Practical wiring of three-pin plugs
Color coding identification exercise
Safety demonstration with earthing

House wiring components
Fuse box model
Different types of fuses
Electrical cables (samples)
Circuit diagrams
Multimeter
Various fuses (2A, 5A, 13A)
Circuit breakers
Fuse wire samples
Electrical appliances
Calculators
Safety equipment samples
Three-pin plugs
Electrical cables
Wire strippers
Screwdrivers
Ring mains circuit model
Color-coded wires
Calculators
Sample electricity bills
Electrical appliances with ratings
Stop watches
Energy meter model
Formula charts

KLB Secondary Physics Form 4, Pages 121-124
KLB Secondary Physics Form 4, Pages 124-125

Mains Electricity

Problem Solving and Applications

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

Solve complex problems on power transmission
Calculate energy consumption for multiple appliances
Analyze electricity costs and savings
Apply knowledge to real-life situations

Review of all chapter concepts
Problem-solving sessions
Group work on complex calculations
Discussion on energy conservation
Preparation for assessment

Calculators
Problem sheets
Past examination questions
Real electricity bills
Energy conservation charts

KLB Secondary Physics Form 4, Pages 117-128