Schooling · Class 7 · Science · Light: Shadows and Reflections · Chapter on a page
CBSE Class 7 · Science · NCERT Curiosity
Light: Shadows and Reflections: chapter on a page
A cut of Shishya's notes for this chapter: the first paragraph of the introduction and the key ideas, formulas and facts, common mistakes and quick revision lists, word for word. Nothing is added or reworded; the worked examples are left out (they are on the chapter page).
About the notes: Written by Shishya's AI on 26 Sept 2026 from the chapter's title and class level, in Shishya's own words — not a copy or summary of the textbook. Read the official chapter for the book's own text, activities and exercises.
This note's current text has no applied fact-check on record.
Mind map
Drawn from the same notes by a fixed rule (no AI): each label is the item's own words — its bold term, its label before a colon, a short formula as written, or its first words.
The mind map as a list
- Key ideas
- Light travels in straight lines.…
- Objects that give out their own…
- Objects that do not give out their…
- Materials through which light can…
- Materials through which light cannot…
- Materials through which light passes…
- A shadow forms when an opaque object…
- Formulas and facts
- Luminous object
- Non-luminous object
- Transparent
- Translucent
- Opaque
- Shadow
- Reflection
- Watch out for
- Thinking all shiny objects are mirrors
- Believing shadows have colour
- Confusing translucent with transparent
- Thinking the shadow always equals…
- Assuming light can bend around…
What this chapter is about
This chapter explores how light travels and what happens when it meets different objects. You will learn why we can see some things clearly through glass but not through a wooden door. You will also discover how shadows form and why they change shape during the day.
Key ideas
- Light travels in straight lines. This is called rectilinear propagation of light.
- Objects that give out their own light are called luminous objects. Examples are the sun, a burning candle and a glowing bulb.
- Objects that do not give out their own light are called non-luminous objects. We see them only when light from a luminous source falls on them and bounces into our eyes.
- Materials through which light can pass completely are called transparent materials. Glass and clear water are transparent.
- Materials through which light cannot pass at all are called opaque materials. Wood, metal and stone are opaque.
- Materials through which light passes only partly are called translucent materials. Oiled paper, frosted glass and thin cloth are translucent.
- A shadow forms when an opaque object blocks the path of light. The shadow appears on the opposite side of the object from the light source.
- When light falls on a smooth, shiny surface like a mirror, it bounces back. This bouncing is called reflection of light.
Formulas and facts to remember
- Luminous object – an object that produces its own light, like the sun or a torch.
- Non-luminous object – an object that does not produce light; we see it by reflected light.
- Transparent – allows almost all light to pass through; objects behind it are clearly visible.
- Translucent – allows some light to pass; objects behind it appear blurry.
- Opaque – does not allow any light to pass; a shadow forms behind it.
- Shadow – a dark region formed when an opaque object blocks light.
- Reflection – the bouncing back of light from a surface.
- Image – what you see when light reflects from a mirror; it looks like the object but is not the object itself.
Common mistakes
- Thinking all shiny objects are mirrors → A shiny metal spoon is curved, so it reflects light differently from a flat mirror; not all shiny surfaces give a clear image.
- Believing shadows have colour → Shadows are simply regions where light is blocked; they do not have colour of their own.
- Confusing translucent with transparent → If you can read a book through the material, it is transparent; if you see only blurred shapes, it is translucent.
- Thinking the shadow always equals the object's size → Shadow size depends on the positions of the light source, the object and the screen.
- Assuming light can bend around corners easily → Light travels in straight lines; it does not curve around opaque objects, which is why shadows have sharp edges.
Quick revision
- Light travels in straight lines; this explains shadow formation.
- Luminous objects make their own light; non-luminous objects only reflect light.
- Transparent lets all light through, translucent lets some, opaque lets none.
- Shadows form on the side opposite the light source.
- Reflection is light bouncing off a surface; a plane mirror shows a laterally inverted image.