Light, Shadows and Reflection Chapter Summary with NCERT Solution Class 7 Chapter 11 2025

Light, Shadows and Reflections – Chapter Summary with NCERT Solution

Light, Shadows and Reflections (AI Generated)

Light helps us see the world around us. Whether it’s sunlight entering our room, a torch beam in the dark, or the reflection we see in a mirror, all these experiences are connected to the science of light, shadows and reflections. This chapter explains how light travels, how shadows form, and how mirrors create images. Learning these concepts helps us understand many everyday observations in a simple and scientific way.

Sources of Light

Light comes from two types of sources:

1. Natural Sources

These are found in nature.

Examples include:

• The Sun (main source of light for Earth)
• Stars
• Lightning
• Fireflies (some animals produce their own light)

2. Artificial Sources

These are man-made.

Examples include:

• Fire and lamps, used since ancient times
• Electric bulbs and tube lights
• LEDs, which save electricity and last longer

Objects that produce their own light are called luminous objects.

Objects that do not produce light are called non-luminous objects.

The Moon is non-luminous because it reflects sunlight and does not make its own light.

Does Light Travel in a Straight Line?

Many simple activities prove that light always travels in a straight line.

• When you align three matchboxes with holes in a straight line, the light passes through all of them.
• But if you move even one box slightly, the light is blocked.

This shows light does not bend as it travels.

Another clear example:

If you look through a straight pipe, you can see the candle flame.

But if you bend the pipe, the flame disappears.

This again proves that light moves in straight lines.

Transparent, Translucent and Opaque Materials

Objects allow light to pass through them differently:

• Transparent materials (glass, clear plastic) allow almost all light to pass.
• Translucent materials (butter paper, frosted glass) allow partial light.
• Opaque materials (wood, metal) do not allow any light to pass.

When we place these objects in the path of light:

• Transparent objects form almost no shadow
• Translucent objects form light, blurry shadows
• Opaque objects form dark, clear shadows

How are Shadows Formed?

A shadow is formed when:

1. There is a light source,
2. An opaque object,
3. And a screen (ground, wall, paper).

When light traveling in a straight line hits an opaque object, the area behind the object where light cannot reach becomes a shadow.

Important points:

• The size of the shadow changes with the distance between the object and the light source.
• Shadow becomes bigger when the object is closer to the light.
• Shadow becomes smaller when the object is far from the light.
• Shadow shape is similar to the object, but colour of the object does not affect the shadow colour.

Reflection of Light

Reflection occurs when light bounces off a shiny surface.

When sunlight falls on a mirror or steel plate, the light gets redirected, forming a bright spot on the wall. This shows that mirrors change the direction of light.

The simplest reflection experiment:

• Shine a thin beam of torchlight through a comb.
• Place a mirror in front of the beam.
• The mirror reflects the beam in a different direction.

Images in a Plane Mirror

A plane mirror forms images with special properties:

• Image is the same size as the object
• Image is upright (erect)
• Image cannot be captured on a screen
• Image shows lateral inversion (left appears right, right appears left)

For example, the word AMBULANCE is written in reverse on the front of the ambulance so that drivers in front can read it correctly in their rear-view mirrors.

Pinhole Camera

A pinhole camera is a simple device that forms an image using a tiny hole.

How it works:

• Light from an object enters through a small hole
• An inverted (upside-down) image forms on a screen inside

This happens because light travels in straight lines and crosses at the pinhole.

Periscope and Kaleidoscope

Periscope

Made using two plane mirrors, it helps us see objects that are not directly in front of us.

Used in:

• Submarines
• Tanks
• Bunkers

Kaleidoscope

Made using three mirrors and colourful objects like beads or broken bangles.

It forms beautiful patterns due to multiple reflections.

Conclusion

Light plays a very important role in our daily life. It helps us see objects, forms shadows, and produces reflections. We learned that:

• Light travels in straight lines
• Opaque objects form shadows
• Mirrors reflect light and form images
• Pinhole cameras create inverted images

Understanding these concepts helps us appreciate things like moonlight, mirrors, torchlight, photos, shadows, and many everyday wonders.

~~~The End~~~

Chapter 11 Light, Shadows and Reflection

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