Discover, Design and Debate — Projects — "Light: Mirrors and Lenses"

1. 13 marksCuriosity Grade 8, Chapter 10, page 169

   Visit a nearby hospital or an ENT specialist's or dentist's clinic. Identify the kind of mirror used to examine the ear, nose, throat and teeth.

   Hint. The chapter has already told you what kind of mirror suits close-up, enlarged viewing inside a small space.

   What to expect, and why. ENT head mirrors and dental mouth mirrors used for close examination are typically concave, for the same reason the chapter gives for the dentist's mirror: a concave mirror which provides an enlarged view of teeth when held close to the teeth inside the mouth. A doctor examining a small, dim, awkward space — an ear canal, the back of a throat, a single tooth — needs the close-up magnification a concave mirror gives, exactly as Activity 10.3 found: when the object is placed close to the mirror, the image is erect but larger.

   ✦ This project asks you to verify a real instrument against the chapter's own reasoning, not to look up a fact blind. Ask the doctor directly which kind of mirror it is and, if possible, why — many head mirrors also have a small hole in the centre to look through while directing light, which is a detail worth recording even though it goes beyond what this chapter covers.

   Record what you actually observe and were told, rather than assuming the answer in advance — a genuine visit might turn up a detail (such as the mirror also being used to reflect light onto the area being examined) that the chapter's own examples do not mention.

2. 24 marksCuriosity Grade 8, Chapter 10, page 169

   Solar cookers use mirrors to converge sunlight and generate heat. Design a solar cooker for your school or home and prepare a proposal including its budget.

   Hint. Base the design on the exact mechanism Activity 10.7 demonstrated, scaled up.

   The underlying principle, straight from the chapter. Devices which concentrate sunlight into a small area, using mirrors and lenses, are called solar concentrators. A solar cooker is exactly this: a concave mirror (or an arrangement of flat mirrors angled to approximate one) converges sunlight onto the cooking vessel, concentrating enough heat there to cook food — the same mechanism, at a larger and safer scale, as the paper igniting in Activity 10.7.

   A proposal to prepare, with the reasoning behind each part:

   Component	Purpose
   A large concave reflector (or several flat mirrors angled to a common point)	Converges sunlight onto one spot, as in Activity 10.7
   A stand that can be tilted to face the Sun	The mirror must face the Sun directly for the beam to converge properly
   A dark-coloured cooking vessel at the focus	Absorbs the concentrated light efficiently as heat
   A budget: materials (reflective sheet or mirror, frame, stand), labour, and a safety cover	Costed realistically for a school or home build

   ✦ The chapter's own framing gives the proposal its purpose, not just its mechanism. In India, such designs are used in villages, thus saving electricity and reducing fossil fuel use. Since the whole point of a solar cooker is to replace fuel or electricity that would otherwise be burned, a complete proposal should state, alongside the design and budget, roughly how much cooking it is meant to support and what it is meant to save.

3. 33 marksCuriosity Grade 8, Chapter 10, page 169

   Use online tools or animation to do virtual experiments with spherical mirrors and lenses, moving objects in the simulation. What should you specifically look for, based on this chapter?

   Hint. Turn the chapter's own activities into a checklist for the simulation.

   A checklist built directly from this chapter's own activities:

   1. Concave mirror: move a virtual object from close to far. Confirm it starts erect and enlarged, and becomes inverted farther away, first growing and then shrinking (Activity 10.3).
   2. Convex mirror: confirm the image stays erect and diminished at every distance you try, only shrinking a little further as distance increases.
   3. Convex lens: repeat the same close-to-far test and confirm the identical pattern — erect and enlarged close up, inverted farther away (Activity 10.9).
   4. Concave lens: confirm the image stays erect and diminished throughout.
   5. Parallel beams: if the simulation allows it, send several parallel rays into each device and watch them converge (concave mirror, convex lens) or diverge (convex mirror, concave lens), as in Activities 10.6 and 10.10.

   ✦ A simulation is most useful as a way to test predictions you have already made from the book, not as a first source of facts. Since this chapter is built entirely on physical activities with real spoons, mirrors and lenses, the value of a virtual version is in confirming that the same patterns hold under conditions you cannot easily arrange at home — very large or very small distances, or a perfectly parallel beam of light — rather than in replacing the hands-on activities altogether.

Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 10 (hecu110.pdf), Reprint 2026-27, pages 152-169. Questions are referenced from the NCERT textbook for identification.