Light Shadows and Reflection Class 6 Questions and Answers

💡 Light Shadows and Reflection Class 6 Questions and Answers

NCERT Chapter 11 with Detailed Solutions

Master Light, Shadows and Reflection for Class 6 Science with comprehensive questions and answers covering luminous bodies, transparent materials, pinhole camera, shadows, and reflection. Each answer is explained in simple, student-friendly language for CBSE exams.

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Light, Shadows and Reflection — Questions & Answers

NCERT Class 6 Science Chapter 11

📘 Quick Reference: Light, Shadows and Reflection

Light: A form of energy that produces the sensation of vision in our eyes. We see objects when light from them enters our eyes.
Luminous Bodies: Objects that emit their own light. Examples: Sun, stars, firefly, burning candle.
Non-Luminous Bodies: Objects that do not emit their own light but become visible when light from a luminous body falls on them. Examples: Moon, book, chair.
Transparent Materials: Allow light to pass through completely; objects can be seen clearly. Examples: Glass, water, air.
Translucent Materials: Allow only some light to pass through; objects appear blurred. Examples: Butter paper, frosted glass, oiled paper.
Opaque Materials: Do not allow any light to pass through. Examples: Wood, iron, stone, cardboard.
Rectilinear Propagation of Light: Light travels in straight lines. This explains why we cannot see around corners.
Shadow: A dark patch formed when an opaque object blocks light. Shadows are formed on the opposite side of the light source.
Umbra: The completely dark part of a shadow where no light reaches.
Penumbra: The partially dark part of a shadow where some light reaches.
Pinhole Camera: A simple camera made from a box with a tiny hole. It forms an inverted (upside-down) and real image on the screen inside.
Reflection: The bouncing back of light from a surface. When light falls on a mirror, it reflects, allowing us to see our image.
Plane Mirror: A flat mirror that forms an erect (upright) and virtual image. The image is the same size as the object, and left-right is reversed.
Eclipse:
- Solar Eclipse: Occurs on a new moon day when the Moon comes between the Sun and Earth.
- Lunar Eclipse: Occurs on a full moon night when the Earth comes between the Sun and Moon.

Key Points to Remember:

Concept	Key Point
Light Travel	Straight line (rectilinear)
Shadow Parts	Umbra (dark) + Penumbra (partial)
Pinhole Image	Inverted and real
Mirror Image	Erect and virtual

💡 Study Tip

When studying this chapter, try simple experiments at home. Use a torch and your hand to make shadows on a wall. Observe how the shadow changes when you move the torch closer or farther. Try making a pinhole camera using a shoebox. These activities will help you understand the concepts better.

Question 1

What is light?

✅ Answer:

Light is a form of energy that produces the sensation of vision in our eyes.

Question 2

Name two luminous bodies.

✅ Answer:

Sun and stars are two luminous bodies.

Question 3

What are non-luminous bodies?

✅ Answer:

Non-luminous bodies are objects that do not emit their own light but become visible when light falls on them. Example: Moon, book.

Question 4

Give two examples of transparent materials.

✅ Answer:

Glass and water are two examples of transparent materials.

Question 5

What are translucent materials?

✅ Answer:

Translucent materials allow only some light to pass through them. Example: butter paper.

Question 6

What are opaque materials?

✅ Answer:

Opaque materials are objects that do not allow any light to pass through them. Example: wood, iron.

Question 7

How does light travel?

✅ Answer:

Light travels in straight lines. This is called rectilinear propagation of light.

Question 8

What is a shadow?

✅ Answer:

A shadow is a dark patch formed when an opaque object blocks light.

Question 9

What is an umbra?

✅ Answer:

Umbra is the completely dark part of a shadow where no light reaches.

Question 10

What is a penumbra?

✅ Answer:

Penumbra is the partially dark part of a shadow where some light reaches.

Question 11

What is a pinhole camera?

✅ Answer:

A pinhole camera is a simple camera made from a box with a tiny hole that forms an inverted image on the screen inside.

Question 12

What type of image is formed by a pinhole camera?

✅ Answer:

A pinhole camera forms an inverted (upside-down) and real image.

Question 13

What is reflection of light?

✅ Answer:

Reflection is the bouncing back of light from a surface. Example: light reflecting from a mirror.

Question 14

Name one object that reflects light.

✅ Answer:

A mirror reflects light.

Question 15

What type of image is formed by a plane mirror?

✅ Answer:

A plane mirror forms an erect (upright) and virtual image.

Question 16

When does a solar eclipse occur?

✅ Answer:

A solar eclipse occurs on a new moon day when the Moon comes between the Sun and Earth.

Question 17

When does a lunar eclipse occur?

✅ Answer:

A lunar eclipse occurs on a full moon night when the Earth comes between the Sun and Moon.

Question 18

Why can't we see objects in the dark?

✅ Answer:

We cannot see objects in the dark because there is no light to reflect from the objects into our eyes.

Question 19

Is the Moon a luminous body?

✅ Answer:

No, the Moon is a non-luminous body. It shines by reflecting sunlight.

Question 20

What is the difference between a shadow and a reflection?

✅ Answer:

A shadow is a dark patch formed when light is blocked. A reflection is the bouncing back of light from a surface.

Question 21

What is the speed of light in air?

✅ Answer:

The speed of light in air is approximately 3 × 10⁸ m/s.

Question 22

Give one example of a natural source of light.

✅ Answer:

The Sun is a natural source of light.

Question 23

Give one example of an artificial source of light.

✅ Answer:

An electric bulb is an artificial source of light.

Question 24

Why do we see our image in a mirror?

✅ Answer:

We see our image in a mirror because light from our body reflects off the mirror and enters our eyes.

Question 25

Name the device used to see objects around a corner.

✅ Answer:

A periscope uses mirrors to see objects around a corner.

Question 26

What happens to the size of a shadow when the object moves closer to the light source?

✅ Answer:

The shadow becomes larger when the object moves closer to the light source.

Question 27

What is the color of a shadow?

✅ Answer:

A shadow is always dark or black in color, regardless of the object's color.

Question 28

Why is a shadow formed?

✅ Answer:

A shadow is formed when light is blocked by an opaque object and cannot pass through it.

Question 29

What type of materials are needed to form a shadow?

✅ Answer:

Opaque materials are needed to form a shadow.

Question 30

Why should we never look at the Sun directly?

✅ Answer:

We should never look at the Sun directly because its bright light can damage our eyes permanently.

Question 1

What is the difference between luminous and non-luminous bodies? Give two examples of each.

✅ Answer:

Luminous bodies: Objects that emit their own light. Examples: Sun, stars, firefly.

Non-luminous bodies: Objects that do not emit their own light but become visible when light from a luminous body falls on them. Examples: Moon, book, chair.

Question 2

Differentiate between transparent, translucent, and opaque materials with examples.

✅ Answer:

Transparent: Allow all light to pass through; objects can be seen clearly. Example: glass, water.

Translucent: Allow only some light to pass through; objects appear blurred. Example: butter paper, frosted glass.

Opaque: Do not allow any light to pass through. Example: wood, iron.

Question 3

Explain the formation of a shadow. What are its two parts?

✅ Answer:

A shadow is formed when an opaque object blocks light. The shadow is formed on the opposite side of the light source.

A shadow has two parts:

Umbra: The completely dark part where no light reaches.
Penumbra: The partially dark part where some light reaches.

Question 4

What is a pinhole camera? What type of image does it form?

✅ Answer:

A pinhole camera is a simple camera made from a box with a tiny hole (pinhole) on one side and a screen on the opposite side. Light from an object passes through the pinhole and forms an inverted (upside-down) and real image on the screen inside the box.

Question 5

What is reflection? How does a plane mirror form an image?

✅ Answer:

Reflection is the bouncing back of light from a surface.

A plane mirror forms an image by reflecting light. The image formed by a plane mirror is:

Erect (upright)
Virtual (cannot be obtained on a screen)
Same size as the object
Left-right reversed

Question 6

Why can't we see objects in a completely dark room?

✅ Answer:

In a completely dark room, there is no light source. We can see objects only when light from a source falls on them and then reflects into our eyes. Without light, no reflection occurs, so we cannot see anything.

Question 7

What is a solar eclipse? When does it occur?

✅ Answer:

A solar eclipse occurs when the Moon comes between the Sun and Earth, blocking sunlight from reaching the Earth. It occurs on a new moon day. During a solar eclipse, the Moon's shadow falls on the Earth.

Question 8

What is a lunar eclipse? When does it occur?

✅ Answer:

A lunar eclipse occurs when the Earth comes between the Sun and Moon, blocking sunlight from reaching the Moon. It occurs on a full moon night. During a lunar eclipse, the Earth's shadow falls on the Moon.

Question 9

What is rectilinear propagation of light? Give an example.

✅ Answer:

Rectilinear propagation of light means that light travels in straight lines.

Example: We cannot see around a corner because light travels in straight lines and cannot bend around the corner to reach our eyes.

Question 10

How can you make a simple pinhole camera?

✅ Answer:

To make a simple pinhole camera:

Take a small cardboard box.
Make a tiny hole (pinhole) in the center of one side.
Make a screen on the opposite side using translucent paper.
Cover the box so no light enters except through the pinhole.
Point the pinhole towards a bright object and observe the image on the screen.

Question 11

What is the difference between a shadow and an image?

✅ Answer:

Shadow: A dark patch formed when light is blocked by an opaque object. It has no details and is always black.

Image: A copy of an object formed by light rays. It shows colors and details. Example: image in a mirror.

Question 12

What are the properties of an image formed by a plane mirror?

✅ Answer:

The properties of an image formed by a plane mirror are:

The image is erect (upright).
The image is virtual (cannot be obtained on a screen).
The image is of the same size as the object.
The image is laterally inverted (left-right reversed).
The image is formed at the same distance behind the mirror as the object is in front.

Question 13

Why is a shadow always dark?

✅ Answer:

A shadow is always dark because it is formed where light is blocked by an opaque object. Since no light reaches that region, it appears dark. The color of the object does not affect the shadow's color.

Question 14

What happens to the size of a shadow when the object is moved away from the light source?

✅ Answer:

When the object is moved away from the light source, the shadow becomes smaller. This is because the object blocks less light when it is farther from the source.

Question 15

Why is it dangerous to look at a solar eclipse with the naked eye?

✅ Answer:

It is dangerous to look at a solar eclipse with the naked eye because the Sun's rays are very intense and can damage the retina of the eye. This can cause permanent blindness. Always use special eclipse glasses or indirect viewing methods.

Question 1

Explain the rectilinear propagation of light. How does it explain the formation of shadows and the working of a pinhole camera?

✅ Answer:

Rectilinear Propagation of Light:
Light travels in straight lines. This property is called rectilinear propagation of light.

Explanation of Shadow Formation:
When an opaque object is placed in the path of light, the light rays cannot pass through it. Since light travels in straight lines, it gets blocked by the object, forming a dark area behind it. This dark area is called a shadow.

Explanation of Pinhole Camera:
In a pinhole camera, light from an object passes through a tiny hole. Since light travels in straight lines, the light from the top of the object goes to the bottom of the screen, and light from the bottom goes to the top. This is why the image formed is inverted.

Conclusion:
The rectilinear propagation of light explains both shadow formation and the working of a pinhole camera.

Question 2

Explain the difference between umbra and penumbra. How are they formed?

✅ Answer:

Umbra:
The umbra is the completely dark part of a shadow where no light from the source reaches. It is formed when the light source is smaller than the opaque object, or when a point source is used.

Penumbra:
The penumbra is the partially dark part of a shadow where some light reaches. It is formed when the light source is larger than the opaque object. The edges of the shadow are not completely dark because light from different parts of the source reaches there.

Formation:

When light from an extended source falls on an opaque object, the region where no light reaches forms the umbra.
The region where light from some parts of the source reaches forms the penumbra.

Conclusion:
A shadow has two parts: the umbra (completely dark) and the penumbra (partially dark).

Question 3

What is reflection of light? Explain the laws of reflection with a simple activity.

✅ Answer:

Reflection of Light:
Reflection is the bouncing back of light from a surface. When light falls on a smooth, shiny surface like a mirror, it reflects back.

Laws of Reflection:

The angle of incidence is equal to the angle of reflection.
The incident ray, reflected ray, and the normal lie in the same plane.

Activity to Demonstrate Reflection:

Take a plane mirror and place it on a table.
Shine a torch at an angle on the mirror.
Observe the reflected light on a wall or paper.
Change the angle of the torch and observe the change in the reflected beam.

Observation:
The reflected beam changes direction when the angle of the torch changes. The angle of incidence equals the angle of reflection.

Conclusion:
Light reflects from surfaces, and the laws of reflection govern this behavior.

Question 4

Explain the difference between solar eclipse and lunar eclipse with the help of diagrams (described in words).

✅ Answer:

Solar Eclipse:
A solar eclipse occurs when the Moon comes between the Sun and Earth. The Moon blocks sunlight from reaching Earth, and its shadow falls on Earth.

Arrangement: Sun → Moon → Earth

Lunar Eclipse:
A lunar eclipse occurs when the Earth comes between the Sun and Moon. The Earth blocks sunlight from reaching the Moon, and its shadow falls on the Moon.

Arrangement: Sun → Earth → Moon

Summary Table:

Feature	Solar Eclipse	Lunar Eclipse
Occurs on	New moon day	Full moon night
Order	Sun → Moon → Earth	Sun → Earth → Moon
Shadow falls on	Earth	Moon

Question 5

What are the different types of materials based on their ability to pass light? Give examples and uses.

✅ Answer:

Based on the ability to pass light, materials are classified into three types:

1. Transparent Materials:
Allow light to pass through completely; objects can be seen clearly.
Examples: Glass, water, air.
Uses: Windows, spectacles, water bottles.

2. Translucent Materials:
Allow only some light to pass through; objects appear blurred.
Examples: Butter paper, frosted glass, oiled paper.
Uses: Lampshades, bathroom windows, privacy screens.

3. Opaque Materials:
Do not allow any light to pass through.
Examples: Wood, iron, stone, cardboard.
Uses: Doors, walls, furniture, boxes.

Question 6

Why do we see our image in a mirror but not in a wall?

✅ Answer:

We see our image in a mirror because the mirror has a smooth, polished surface that reflects light uniformly. When light from our body falls on the mirror, it reflects back in an organized way, forming a clear image.

A wall has a rough surface. When light falls on a wall, it scatters in different directions. This is called diffuse reflection. Because the light does not reflect uniformly, no clear image is formed.

Conclusion:
Mirrors form images because of regular reflection, while walls do not form images because of diffuse reflection.

Question 7

Explain the working of a pinhole camera. What happens to the image when the size of the hole is increased?

✅ Answer:

Working of a Pinhole Camera:
A pinhole camera consists of a box with a tiny hole on one side and a screen on the opposite side. Light from an object passes through the pinhole and falls on the screen. Since light travels in straight lines, the image formed is inverted (upside-down) and real.

Effect of Increasing Hole Size:
When the size of the hole is increased, more light enters the box. However, the image becomes blurred. This is because light from different points on the object overlaps on the screen. A small hole ensures that only a thin beam of light from each point passes through, forming a sharp image.

Conclusion:
A pinhole camera works on the principle of rectilinear propagation of light. A smaller hole gives a sharper image, while a larger hole makes the image blurred.

Question 8

How can you measure the length of a shadow? What factors affect the size of a shadow?

✅ Answer:

Measuring the Length of a Shadow:

Place an opaque object in the path of a light source.
Mark the starting point of the shadow and the ending point.
Use a measuring tape or scale to measure the distance between the two points.

Factors Affecting the Size of a Shadow:

Distance between object and light source: Moving the object closer to the light source makes the shadow larger; moving it farther makes it smaller.
Distance between object and screen: Moving the screen farther from the object makes the shadow larger.
Size of the object: A larger object forms a larger shadow.
Angle of the light source: The angle at which light falls also affects the shadow's size and shape.

Question 9

What is a plane mirror? Explain its uses in daily life.

✅ Answer:

Plane Mirror:
A plane mirror is a flat, smooth, and polished surface that reflects light. It forms an erect (upright) and virtual image of the same size as the object. The image is laterally inverted (left-right reversed).

Uses of Plane Mirrors in Daily Life:

Looking glass: Used at home for personal grooming.
Periscope: Used in submarines to see objects above the water surface.
Rear-view mirror: Used in vehicles to see traffic behind.
Dentist's mirror: Used by dentists to see the back of teeth.
Optical instruments: Used in telescopes and microscopes.
Decoration: Used in showrooms and homes to create an illusion of space.

Question 10

Describe an activity to show that light travels in straight lines.

✅ Answer:

Activity to Show Rectilinear Propagation of Light:

Materials needed:

Three cardboard pieces of the same size
A candle or torch
A stand or holder

Procedure:

Make a small hole in the center of each cardboard piece.
Place the three cardboards in a straight line such that their holes are aligned.
Place a lit candle on one side of the cardboards.
Look through the holes from the other side. You will be able to see the candle flame.
Now, move one cardboard slightly to the side so that the holes are no longer in a straight line.
Look through the holes again. You will not be able to see the candle flame.

Observation:
When the holes are aligned, the flame is visible. When one cardboard is displaced, the flame is not visible.

Conclusion:
This activity shows that light travels in straight lines. When the path is blocked by displacing a cardboard, light cannot reach our eyes.

📘 Quick Revision: Light, Shadows and Reflection

Light: Form of energy that produces vision.
Luminous: Emit own light (Sun). Non-luminous: Reflect light (Moon).
Transparent: Allow all light (glass). Translucent: Allow some light (butter paper). Opaque: Allow no light (wood).
Rectilinear Propagation: Light travels in straight lines.
Shadow: Dark patch behind an opaque object. Has umbra (dark) and penumbra (partial).
Pinhole Camera: Forms inverted and real image.
Reflection: Bouncing back of light. Plane mirror forms erect and virtual image.
Eclipses: Solar (new moon), Lunar (full moon).