Light And Shadow - Class 5 Science - New St. Mery English School

Light is an important part of our daily life. Without light, we would not be able to see anything around us. The Sun is the main natural source of light, while bulbs, candles, and tube lights are artificial sources of light. When light falls on an object, it can pass through, get blocked, or form a shadow.

In this chapter, we will learn how shadows are formed and why they change in size and shape. We will also understand the difference between transparent, translucent, and opaque objects. Fun activities and simple examples will help us explore how light travels and how shadows are created in our surroundings.

Light And Shadow - Class 5 Science - New St. Mery English School

What is Light?

Ans:- Light is a form of energy that helps us see things.

What are sources of light?

Ans:- The things that produce their own light are called sources of light.

Ex:- bulb, sun, stars etc 

How many types of sources of light?

Ans:- There are two types of sources of light.

1- Natural sources of light

2- Artificial sources of light

What are Natural sources of light?

Ans:- Natural sources of light are things in nature that produce their own light without being made by humans.

Ex:- Sun, Stars, glow worm etc.

What are Artificial sources of light?

Ans:- The man made things that produce light are called Artificial sources of light.

Ex:- electric bulb, torch, candles etc.

Write three properties of light?

Ans:- Three properties of light are

1- Light travels in straight line. This is called rectilinear propagation of light.

2- Light travels from one place to another.

3- White light is made up of seven colours.

What is Rainbow?

Ans:- When sunlight passes through rain drops, It splits into seven colours and makes a band of seven colours. This band of seven colours are Rainbow. It forms in the sky. The seven colours of rainbow are violet, indigo, blue, green, yellow, orange, and red (VIBGYOR)

How many types of objects on the basis of amount of light they allow to pass through them?

Ans:- There are three types of objects on the basis of amount of light they allow to pass through them.

1- Transparent objects

2- Translucent objects

3- opaque objects

What are transparent objects?

Ans:- Some objects that allow light to pass through them easily are called transparent objects.

Ex:- glass, water etc.

What are translucent objects?

Ans:- Objects through which only some light can pass are called translucent objects.

Ex:- Butter paper, frosted glass, thin cloth, oiled paper

What are opaque objects?

Ans:- Some objects that do not allow light to pass through them are called opaque objects.

Ex:- wood, stone etc.

What is shadow?

Ans:- A shadow is a dark patch formed when an object blocks the path of light. It is always formed on the opposite side to the source of light.

Write three conditions that is necessary for the formation of shadow.

Ans:- The three conditions that is necessary for the formation of shadow are

1- A light source

2- An opaque object

3- A surface such as wall, floor, table top etc.

Write five properties of shadow.

Ans:- The five properties of shadow are

1- The shadow is formed when light falls on an opaque or translucent object.

2- A shadow is formed on the opposite side of the source of light.

3- Shadow do not depend on the colour of the object. It is mostly black.

4- A shadow shows only the shape of the object and not its details.

5- The size of the shadow depends on the distance between the source of light and the object.

 Light - Class 7 Science - New St. Mery English School

Light is a form of energy that enables us to see the beautiful world around us. Without light, everything would appear dark and invisible. The Sun is the main natural source of light for the Earth, while electric bulbs, candles, and tube lights are artificial sources of light.

Light travels in a straight line and helps us understand important concepts like reflection, shadows, and images formed by mirrors. When light falls on an object, it may be reflected, absorbed, or pass through it. This is why some objects are transparent, some are translucent, and others are opaque.

In this chapter, we will learn about sources of light, reflection of light, mirrors, and how light helps us see objects clearly. Let us explore the amazing properties of light and understand how it plays an important role in our daily life.

Light - Class 7 Science - New St. Mery English School

What is Light ?

Ans:- Light is the form of electromagnetic energy that makes everything visible. It can detected by human eyes.

What is rectilinear propagation of light?

Ans:- When light moves from one place to another, it follows a straight path as long as it travels through the same medium. This property of light is known as rectilinear propagation of light.

Ex:- When you switch on a torch in a dark room, the beam of light goes straight. You can see a straight line of light — that shows rectilinear propagation.

🌑 Shadow Formation

Shadows are formed because light travels in straight lines.
If an object comes in the path of light, it blocks the light and a shadow forms behind it.

Rectilinear propagation of light happens only when light travels in a uniform medium. When it changes medium (like air to water), it bends. That bending is called refraction.

Write an experiment that show that light travel in straight path

🎯 Aim

To prove that light travels in a straight path.

🧰 Materials Required

• 3 pieces of cardboard

• A candle

• Matchbox

• A table

🛠 Procedure

1. Take three cardboards of the same size.

2. Make a small hole at the center of each cardboard.

3. Fix the three cardboards vertically on a table in such a way that the holes are at the same height.

4. Place the cardboards in a straight line, one behind the other.

5. Put a lighted candle behind the first cardboard.

6. Look through the hole of the third cardboard from the other side.

👀 Observation

• When all three holes are in one straight line, the flame of the candle is clearly visible.

• If you move any one cardboard slightly to the side, the candle flame cannot be seen.

🧠 Conclusion

This experiment shows that light travels in a straight line. When the holes are aligned, light passes straight through them. When the path is disturbed, light cannot bend around the cardboard to reach the eye.

Reflection of light

When light hits an object like a mirror, it does not pass through. Instead, it returns back into the same medium. This is called reflection of light.

Types of Reflection

There are two types of reflection of light

1- Regular Reflection

2- Irregular Reflection

Regular Reflection

Regular reflection happens when light rays fall on a smooth, polished surface and reflect in an orderly, parallel way. In regular reflection parallel rays of light hit a smooth surface and the reflected rays also remain parallel.

Ex:- A plane mirror gives regular reflection. That’s why you can see a clear image of yourself in it.

Irregular Reflection

Irregular reflection happens when light falls on a rough surface and reflects in many different directions. In irregular reflection parallel rays of light hit a rough surface and the reflected rays scatter in different directions.

Ex:- When light strike on a wall it gives Irregular reflection, Reflection of light in water

ray of light?
Ans:- A ray of light is a narrow stream (प्रबहित होना ) of light that represents the path along which light energy travels in a medium is called ray of light.  it is represented by a straight line and an arrow marked on it. the arrow represents the direction of ray of light

beam of light?
Ans:- A group of light rays is called beam of light.

 types of beam of light?
Ans:- There are three types of beam of light.
           1- Parallel beam of light
           2- Convergent beam of light
           3 - Divergent beam of light

Parallel beam of light?
Ans:- When the rays of light travel parallel to each other then the collection of such rays is called parallel beam of light .

convergent beam of light?
Ans:- When the rays of light coming from the different directions and meat at a specific point then the collection of such rays is called convergent beam of light.

divergent beam of light?

Ans:- When the rays of light emerge from a point source of light and travel in different direction , such beam of light is called divergent beam of light.

What is incident ray?
Ans:- A ray of light that is coming from source of light towards the reflecting surface is called incident ray of light.

What is reflecting ray?
Ans:- A ray of light bouncing away from the reflecting surface after reflection is called reflecting ray.

What is point of incident?
Ans:- The point on a reflecting surface where incident ray, reflecting ray and normal meet together is called point of incident.

What is normal?
Ans:- A line drawn perpendicular to the reflecting surface is called normal.

What is incidence angle?
Ans:- An angle which is formed between incident ray and normal is called incidence angle. It is represented by ' i ' 

Incidence angle = ∠i

What is reflected angle?
Ans:- An angle which is formed between normal and reflected ray is called reflected angle. It is represented by ' r '.

Reflected angle = ∠r 

What are the 2 Laws of reflection of light?  

Ans:- The two laws of reflection are

1- The incident ray, the normal at the point of incidence and the reflected ray all lie in the same plane.

2-The angle of incidence is equal to the angle of reflection. , ∠i  = ∠r .

Image

An image is the picture of an object formed when light rays coming from the object reflect from a mirror or refract through a lens and reach our eyes.

Real image

The image that can be obtained on a screen is called real image

Virtual image

The image that can not be obtained on a screen is called virtual image

What is mirror?

Ans:- Any smooth polished surface which can turn the rays of light back into the same medium is called mirror.

Ex:- looking glass, highly polished metal, still water, still oil etc

How many types of mirror?

Ans:- There are two types of mirror.

1- Plane Mirror

2- Spherical Mirror

What is Plane Mirror?

Ans:- A plane mirror is a flat and smooth surface that reflects light to form an image. A plane mirror forms an image that is virtual, erect, Laterally inverted and Same size of the object.

Light, Sound and Force - Class 3 Science - New St. Mery English School

Light, Sound, and Force are three wonderful gifts of nature that help us understand the world around us. From seeing colorful objects, hearing sweet sounds, to pushing and pulling things—these three play an important role in our daily life.

Light helps us to see. Without light, everything would be dark. The Sun, candles, and electric bulbs are sources of light.
Sound helps us to communicate and enjoy music. We hear sounds when something vibrates.
Force is a push or a pull that makes objects move, stop, change shape, or change direction.

In this chapter, students will learn how light, sound, and force work, where they come from, and how they help us in everyday life. This lesson is designed in a fun and simple way so that Class 3 students can easily understand these basic science concepts and enjoy learning. 🌟

Light, Sound and Force - Class 3 Science - New St. Mery English School 

What is Light?

Ans:- Light is a form of energy that helps us see things.

How many types of object on the basis of Light?

Ans:- There are two types of object on the basis of Light.

1- Luminous object

2- Non-Luminous object

What are Luminous Objects?

Ans:- The objects that give us light are called Luminous Objects.

Ex:- sun, bulb, torch and candle etc

How many types of Luminous object?

Ans:- There are two types of luminous object.

1- Natural luminous object

2- Man-made luminous object

What are Natural Luminous objects?

Ans:- Objects that give out light by themselves and are not man-made are called natural luminous objects.

Ex:- sun, stars, fire, lightning, fireflies etc.

What are Man-made luminous objects?

Ans:- The luminous objects that are made by man are called Man-made luminous objects.

Ex:- bulb, torch and candle etc.

What are Non-Luminous object?

Ans:- Objects that cannot give out light by themselves are called non-luminous objects.

Ex:- book, table, chair, moon, ball etc.

What are transparent objects?

Ans:- Some objects that allow light to pass through them easily are called transparent objects.

Ex:- glass, water etc.

What are translucent objects?

Ans:- Objects through which only some light can pass are called translucent objects.

Ex:- Butter paper, frosted glass, thin cloth, oiled paper

What are opaque objects?

Ans:- Some objects that do not allow light to pass through them are called opaque objects.

Ex:- wood, stone etc.

What is shadow?

Ans:- A shadow is a dark patch formed when an object blocks the path of light. It is always formed on the opposite side to the source of light.

Write three conditions that is necessary for the formation of shadow.

Ans:- The three conditions that is necessary for the formation of shadow are

1- A light source

2- An opaque object

3- A surface such as wall, floor, table top etc.

Write three properties of shadow.

Ans:- The three properties of shadow are

1- The shape of shadow is similar to the shape of object

2- The size can be smaller or bigger than the object.

3- Shadow are always black in colour.

What is Sound?

Ans:- Sound is a form of energy that is produced by vibrations and travels through a medium like air, water, or solids as sound waves.

How many types of sound?

Ans:- There are two types of sound.

1- Pleasant sound

2- Unpleasant sound

What is Pleasant Sound?

Ans:- The sound which makes us feel good is called Pleasant Sound.

Ex:- Musical sounds, Chirping of the birds

What is Unpleasant sound?

Ans:- The sound which makes us uncomfortable is called unpleasant sound.

Ex:- Sound of a drill machine, bursting of loud fire crackers, The honking of vehicles

What is noise?

Ans:- The loud and unpleasant sound is called noise. Noise is harmful for our health.

What is Force?

Ans:- Force is a push or pull on an object. It can not be seen or touched. But you can feel it. You can also use it to do many things.

Write four effects of Force.

Ans:- The four effects of force are

1- A force can move an object.

2- It can change the shape of an object

3- It can slow down or stop a moving object.

4- It can change the direction of a moving object.