Force and Energy

Curved Mirrors - Types of curved mirrors: concave, convex and parabolic

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

- Identify and distinguish between concave, convex and parabolic curved mirrors
- Describe the three types of curved mirrors based on the direction their reflecting surfaces curve
- Show interest in observing curved mirrors in the everyday environment

- Study pictures of different types of mirrors and identify which represent curved mirrors; discuss the meaning of a curved mirror
- Use mirrors provided by the teacher to identify concave mirrors (surface curved inwards, converging) and convex mirrors (surface curved outwards, diverging)
- Discuss parabolic surfaces: ability to converge or diverge all incident light rays at the focal point (Figures 3.1–3.3)

What is a curved mirror and how do the three types differ in the direction of their reflecting surfaces?

- Spotlight Integrated Science pg. 129
- Different types of mirrors, charts of mirror types
- Reference books

- Observation - Oral questions - Written assignments

Force and Energy

Curved Mirrors - Terms used in curved mirrors: concave mirror

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

- Define and identify the terms associated with a concave mirror: pole (P), principal axis, centre of curvature (C), radius of curvature, principal focus (F), focal length and focal plane
- Draw a labelled diagram of a concave mirror showing all associated terms
- Appreciate the importance of precise terminology in describing curved mirrors

- Use print or digital media to search for the meaning of terms: focal length, radius of curvature, principal axis, centre of curvature, focal plane, pole, aperture and principal focus; write short notes
- Draw a circle of radius 3 cm, label C, draw the principal axis, mark P, construct the perpendicular bisector of CP and label F; measure and record FP (focal length) and CP (radius of curvature)
- Discuss the relationship: focal length = radius of curvature ÷ 2; share diagrams with classmates

What does each term used to describe a concave mirror represent and how are they related to each other?

- Spotlight Integrated Science pg. 131
- Pencil, ruler, compass, plain paper, reference books
- Digital resources

- Observation - Oral questions - Written assignments

Force and Energy

Curved Mirrors - Terms used in curved mirrors: convex mirror and focal length

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

- Define and identify terms associated with a convex mirror: pole, principal axis, centre of curvature, principal focus and focal length
- Determine the focal length of a concave mirror experimentally and calculate the radius of curvature
- Show interest in using experimental methods to determine the properties of curved mirrors

- Draw a convex mirror diagram (radius 3 cm): label C (behind mirror), principal axis, P, construct perpendicular bisector of CP and label F; note that C and F are behind the mirror for a convex mirror
- Set up the focal length experiment: place a concave mirror on a stand facing a distant object; move a white screen until a sharp inverted image forms; measure and record the distance between the mirror and the screen (Table 3.1); repeat three times and calculate the average focal length
- Solve the worked example: mirror gives sharp image at 22 cm — state the focal length and calculate the radius of curvature

How is the focal length of a concave mirror determined experimentally and how does it relate to the radius of curvature?

- Spotlight Integrated Science pg. 132
- Concave mirror, metre rule, white screen, mirror holder, distant object
- Reference books

- Observation - Oral questions - Written assignments

Force and Energy

Curved Mirrors - Rules of reflection: three special rays

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

- State and apply the three rules of reflection for curved mirrors: ray parallel to principal axis, ray through centre of curvature, ray through principal focus
- Draw ray diagrams showing each rule for both concave and convex mirrors
- Appreciate that predictable ray behaviour is the foundation for locating images in curved mirrors

- Investigate Ray 1: draw a ray parallel and close to the principal axis; show it reflects through F (concave) or appears to diverge from F (convex) — Figures 3.10 and 3.11
- Investigate Ray 2: draw a ray through C; show it reflects back along the same path in a concave mirror; show it appears to come from C as a broken line in a convex mirror — Figures 3.14 and 3.15
- Investigate Ray 3: draw a ray through F (concave) or appearing to pass through F (convex); show it reflects parallel to the principal axis — Figures 3.16–3.18

How does knowing how three special rays behave after reflection allow us to locate any image formed by a curved mirror?

- Spotlight Integrated Science pg. 135
- Pencil, 30 cm ruler, plain paper, exercise book
- Charts of ray diagrams (Figures 3.10–3.18)

- Observation - Written assignments - Oral questions

Force and Energy

Curved Mirrors - Image location: object beyond C and object at C

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

- Draw ray diagrams to locate the image formed when an object is placed beyond C in a concave mirror
- Draw ray diagrams to locate the image formed when an object is placed at C in a concave mirror
- State the characteristics of the image formed in each case

- Draw Figure 3.20 (object beyond C): use Ray 1 (parallel → through F) and Ray 2 (through F → parallel); locate intersection; state characteristics: image between C and F, real, inverted, smaller than object
- Draw Figure 3.22 (object at C): apply the same two rays; locate intersection at C; state characteristics: image at C, real, inverted, same size as object
- Discuss why the image moves closer to F as the object moves farther from C; share and compare diagrams with classmates

What happens to the image of an object in a concave mirror as the object moves from beyond C to exactly at C?

- Spotlight Integrated Science pg. 140
- Pencil, 30 cm ruler, plain paper, exercise book
- Charts of ray diagrams

- Observation - Written assignments - Oral questions

Force and Energy

Curved Mirrors - Image location: object between C and F, and object at F

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

- Draw ray diagrams to locate the image when an object is placed between C and F in a concave mirror
- Draw a ray diagram to show image formation when an object is placed at F in a concave mirror
- State the characteristics of images formed in each case including the special case at F

- Draw Figure 3.24 (object between C and F): apply Ray 1 and Ray 2; locate intersection beyond C; state characteristics: image beyond C, real, inverted, larger than object
- Draw Figure 3.26 (object at F): apply Ray 1 and Ray through C; show reflected rays are parallel (no intersection); discuss result: image at infinity, no image can be focused on a screen
- Discuss the pattern: as object moves from C towards F, image moves from C towards infinity and grows larger

Why does placing an object at the principal focus of a concave mirror produce no focused image on a screen?

- Spotlight Integrated Science pg. 145
- Pencil, 30 cm ruler, plain paper, exercise book
- Charts of ray diagrams

- Observation - Written assignments - Oral questions

Force and Energy

Curved Mirrors - Image location: object between F and P, and convex mirror

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

- Draw ray diagrams to locate the image when an object is placed between F and P in a concave mirror
- Draw ray diagrams to locate images formed by a convex mirror for any object position
- Distinguish between real and virtual images in curved mirrors

- Draw Figure 3.28 (object between F and P): extend reflected rays behind mirror with dotted lines; locate virtual intersection behind mirror; state characteristics: virtual, behind mirror, upright, larger than object
- Draw Figure 3.35 (convex mirror): use Ray 1 (parallel → appears from F) and Ray 3 (appears through C → reflected back); extend dotted virtual rays behind mirror; state characteristics: virtual, between P and F, upright, smaller than object (Figure 3.38)
- Discuss: concave mirrors can form both real and virtual images depending on object position; convex mirrors always form virtual images

How does the position of an object in front of a concave mirror determine whether the image formed is real or virtual?

- Spotlight Integrated Science pg. 148
- Pencil, 30 cm ruler, plain paper, exercise book
- Charts of ray diagrams

- Observation - Written assignments - Oral questions

Force and Energy

Curved Mirrors - Practical: characteristics of images in a concave mirror
Curved Mirrors - Practical: characteristics of images in a convex mirror and summary

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

- Investigate experimentally the characteristics of images formed by a concave mirror when an object is placed at various positions
- Record and interpret observations of image size, nature (real/virtual) and orientation at each object position
- Appreciate that systematic experimentation confirms the predictions made from ray diagrams

- Set up the practical (Figure 3.42): concave mirror on stand, mark C and F on a metre rule; place a lit candle beyond C; adjust screen until sharp image forms; observe and record size (smaller), nature (real) and orientation (inverted)
- Repeat for object at C (same size, real, inverted), between C and F (larger, real, inverted); note that no image forms on screen when object is at F or between F and P
- Discuss results and confirm they match the predictions from ray diagrams; complete a summary table of all object positions and corresponding image characteristics

How does experiment confirm what ray diagram theory predicts about image formation in a concave mirror?

- Spotlight Integrated Science pg. 152
- Concave mirror with known focal length, candle, lighter, screen, metre rule, mirror holder
- Reference books
- Spotlight Integrated Science pg. 153
- Convex mirror with known focal length, candle, screen, metre rule, mirror holder

- Observation - Written assignments - Oral questions

Force and Energy

Curved Mirrors - Uses of concave and convex mirrors

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

- State the uses of concave mirrors: shaving mirrors, dentist's mirrors, torches, car headlamps, microscope condensers, solar concentrators and telescopes
- State the uses of convex mirrors: car side mirrors and supermarket security mirrors
- Relate the specific properties of each mirror type to why it is used in each application

- Study pictures A–D showing uses of curved mirrors; identify each application and discuss how the mirror property (concave: magnification/focus; convex: wide field of view) makes it suitable
- Discuss uses of concave mirrors: shaving mirror (magnified upright image), dentist's mirror (magnified image of teeth), torch/headlamp (parallel beam from object at F), solar concentrator (focuses sunlight to one point), telescope (sees faraway objects)
- Discuss uses of convex mirrors: car side mirror (wide field of view behind vehicle), supermarket security mirror (covers all walkways); make a poster showing the importance of side mirrors in road safety

Why does a supermarket use a convex mirror rather than a concave mirror for security purposes?

- Spotlight Integrated Science pg. 154
- Charts of mirror applications, pictures A–D
- Reference books

- Oral questions - Written assignments - Observation

Force and Energy

Curved Mirrors - Uses of concave and convex mirrors

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

- State the uses of concave mirrors: shaving mirrors, dentist's mirrors, torches, car headlamps, microscope condensers, solar concentrators and telescopes
- State the uses of convex mirrors: car side mirrors and supermarket security mirrors
- Relate the specific properties of each mirror type to why it is used in each application

- Study pictures A–D showing uses of curved mirrors; identify each application and discuss how the mirror property (concave: magnification/focus; convex: wide field of view) makes it suitable
- Discuss uses of concave mirrors: shaving mirror (magnified upright image), dentist's mirror (magnified image of teeth), torch/headlamp (parallel beam from object at F), solar concentrator (focuses sunlight to one point), telescope (sees faraway objects)
- Discuss uses of convex mirrors: car side mirror (wide field of view behind vehicle), supermarket security mirror (covers all walkways); make a poster showing the importance of side mirrors in road safety

Why does a supermarket use a convex mirror rather than a concave mirror for security purposes?

- Spotlight Integrated Science pg. 154
- Charts of mirror applications, pictures A–D
- Reference books

- Oral questions - Written assignments - Observation

Force and Energy

Curved Mirrors - Applications of curved mirrors in day-to-day life

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

- Describe the broader applications of curved mirrors including solar cookers, projector lamps and road safety devices
- Solve structured problems on curved mirrors involving image position and characteristics
- Appreciate the wide range of practical applications of curved mirrors in modern life

- Read the journal excerpt (Therono's solar cooker) and write personal ways curved mirrors are used in daily life; present findings to the class
- Solve structured questions from the assessment activity: label parts of concave and convex mirror diagrams; explain the importance of a driving mirror; answer the magic mirror question (top to bottom: convex → plane → concave); explain why headlights use concave reflectors; describe characteristics of the image Winnie saw in the motorcycle side mirror
- Discuss: using knowledge of mirrors, design a simple solar cooker at home with guidance from a parent or guardian

How can knowledge of curved mirrors be applied to solve real-life engineering and safety problems?

- Spotlight Integrated Science pg. 155
- Reference books
- Digital resources

- Written tests - Oral questions - Observation

Force and Energy

Curved Mirrors - Applications of curved mirrors in day-to-day life

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

- Describe the broader applications of curved mirrors including solar cookers, projector lamps and road safety devices
- Solve structured problems on curved mirrors involving image position and characteristics
- Appreciate the wide range of practical applications of curved mirrors in modern life

- Read the journal excerpt (Therono's solar cooker) and write personal ways curved mirrors are used in daily life; present findings to the class
- Solve structured questions from the assessment activity: label parts of concave and convex mirror diagrams; explain the importance of a driving mirror; answer the magic mirror question (top to bottom: convex → plane → concave); explain why headlights use concave reflectors; describe characteristics of the image Winnie saw in the motorcycle side mirror
- Discuss: using knowledge of mirrors, design a simple solar cooker at home with guidance from a parent or guardian

How can knowledge of curved mirrors be applied to solve real-life engineering and safety problems?

- Spotlight Integrated Science pg. 155
- Reference books
- Digital resources

- Written tests - Oral questions - Observation

Force and Energy

Curved Mirrors - Review and self-assessment: Sub-strand 3.1

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

- Summarise types of curved mirrors, terms used, ray diagram rules, image characteristics and uses of curved mirrors
- Solve structured review questions linking mirror type and object position to image characteristics
- Reflect on personal progress using the self-assessment table for sub-strand 3.1

- Attempt review questions: draw and label a concave and convex mirror; draw ray diagrams for an object at two different positions; state characteristics of images formed; explain why a concave mirror is used in a car headlamp but a convex mirror in a car side mirror
- Discuss answers as a class and address common errors in ray diagram construction
- Self-assess using the self-assessment table (Table 3.2) for sub-strand 3.1 and identify areas needing improvement

How well do I understand the formation of images in curved mirrors and their applications in daily life?

- Spotlight Integrated Science pg. 157
- Reference books
- Past exercises

- Written tests - Self-assessment - Oral questions

Force and Energy

Curved Mirrors - Review and self-assessment: Sub-strand 3.1

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

- Summarise types of curved mirrors, terms used, ray diagram rules, image characteristics and uses of curved mirrors
- Solve structured review questions linking mirror type and object position to image characteristics
- Reflect on personal progress using the self-assessment table for sub-strand 3.1

- Attempt review questions: draw and label a concave and convex mirror; draw ray diagrams for an object at two different positions; state characteristics of images formed; explain why a concave mirror is used in a car headlamp but a convex mirror in a car side mirror
- Discuss answers as a class and address common errors in ray diagram construction
- Self-assess using the self-assessment table (Table 3.2) for sub-strand 3.1 and identify areas needing improvement

How well do I understand the formation of images in curved mirrors and their applications in daily life?

- Spotlight Integrated Science pg. 157
- Reference books
- Past exercises

- Written tests - Self-assessment - Oral questions

Force and Energy

Curved Mirrors - CAT: Sub-strand 3.1

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

- Demonstrate mastery of sub-strand 3.1 through a written class assessment test
- Apply knowledge of mirror types, terms, ray diagrams, image characteristics and uses in structured questions
- Show honesty and diligence during the assessment

- Complete a written class assessment test covering: types of curved mirrors, terms used in curved mirrors, drawing ray diagrams for different object positions in concave and convex mirrors, image characteristics, uses and applications of curved mirrors
- Submit work for teacher marking
- Receive written feedback and set personal improvement targets

How well can I apply my knowledge of curved mirrors in answering structured questions?

- Spotlight Integrated Science pg. 157
- Assessment paper
- Reference books

- Written test - Marking and feedback

Force and Energy

Curved Mirrors - CAT: Sub-strand 3.1

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

- Demonstrate mastery of sub-strand 3.1 through a written class assessment test
- Apply knowledge of mirror types, terms, ray diagrams, image characteristics and uses in structured questions
- Show honesty and diligence during the assessment

- Complete a written class assessment test covering: types of curved mirrors, terms used in curved mirrors, drawing ray diagrams for different object positions in concave and convex mirrors, image characteristics, uses and applications of curved mirrors
- Submit work for teacher marking
- Receive written feedback and set personal improvement targets

How well can I apply my knowledge of curved mirrors in answering structured questions?

- Spotlight Integrated Science pg. 157
- Assessment paper
- Reference books

- Written test - Marking and feedback