Grade 6
  1. Introduction to Physics  1.1. What is physics?  1.2. Importance of physics in daily life  1.3. Scientific Method  1.4. Measurement in Science  1.5. Branches of physics
  2. Measurement and units  2.1. Physical quantities  2.2. SI units  2.3. foot length  2.4. Measuring mass  2.5. Measuring time  2.6. Measuring volume  2.7. Measuring Temperature  2.8. Accuracy and precision in measurements  2.9. Instruments Used for Measurement  2.10. Estimation and approximation in measurement
  3. Force and Speed  3.1. Introduction to force  3.2. Types of forces  3.3. Effect of forces  3.4. Contact and non-contact forces  3.5. Gravity and its effects  3.6. Friction and its effects  3.7. Speed and types of speed  3.8. Speed and Velocity  3.9. Acceleration  3.10. Newton's laws of motion  3.11. Simple machines and their uses  3.12. Work, power and their relation
  4. Energy  4.1. Introduction to Energy  4.2. Types of energy  4.3. Potential and Kinetic Energy  4.4. Law of conservation of energy  4.5. Energy conversion  4.6. Energy sources  4.7. Renewable and non-renewable energy sources  4.8. Energy conversion efficiency
  5. Lighting and Optics  5.1. Introduction to Lighting  5.2. Properties of light  5.3. Reflection of light  5.4. Laws of reflection  5.5. Refraction of light  5.6. Lenses and their uses  5.7. Creation of shadows  5.8. Dispersion of light and the colour spectrum  5.9. Human eye and vision  5.10. Optical Instruments
  6. Sound  6.1. Introduction to sound  6.2. How is sound produced?  6.3. Transmission of sound  6.4. Sound characteristics  6.5. Pitch and loudness  6.6. Speed of sound in different mediums  6.7. Reflection of sound and echo  6.8. Applications of sound in daily life  6.9. Ultrasound and its uses
  7. Heat and temperature  7.1. Introduction to heat  7.2. Temperature and its measurement  7.3. Heat transfer methods  7.4. Conductivity  7.5. Convection  7.6. Radiation  7.7. Effect of heat on matter  7.8. Expansion and contraction  7.9. Thermal conductors and insulators  7.10. Specific heat capacity
  8. Electricity and Magnetism  8.1. Introduction to Electricity  8.2. Electrical Circuits and Components  8.3. Conductors and Insulators  8.4. Introduction to Magnetism  8.5. Properties of magnets  8.6. Magnetic Field  8.7. Electromagnets and their uses  8.8. simple electrical circuit  8.9. Static electricity  8.10. Electrical Safety and Precautions
  9. Matter and its properties  9.1. Introduction to matter  9.2. States of matter  9.3. Properties of Solids  9.4. Properties of Liquids  9.5. Properties of gases  9.6. Change in state of matter  9.7. Expansion and contraction of matter  9.8. Density and its calculation
  10. Space and the solar system  10.1. Introduction to Space Science  10.2. Planets of the Solar System  10.3. Sun as a source of energy  10.4. Phases of the Moon  10.5. Rotation and revolution of the earth  10.6. Solar and lunar eclipses  10.7. Satellites and their uses  10.8. Asteroids, comets and meteors
  11. Environmental Physics  11.1. Impact of human activities on the environment  11.2. Energy conservation  11.3. Renewable energy sources  11.4. Climate change and its effects  11.5. Pollution and measures to reduce it  11.6. Greenhouse effect and global warming  11.7. Sustainable Development

Grade 6 → Lighting and Optics ↓


Creation of shadows


In the world of light and optics, shadows are fascinating phenomena that help us understand how light travels and interacts with different objects. A shadow is a dark area or shape that forms when an object blocks light from reaching a surface.

To understand shadows, we first need to understand the basic properties of light. Light travels in straight lines, and this property is important for the formation of shadows. When something blocks light, it prevents some of the light from traveling forward, creating a shadow.

Basic principles of light and shadow

Light sources, such as the sun, light bulbs, and candles, emit light rays that travel outward in straight lines in all directions. When these light rays hit an object, they can behave in different ways depending on the nature of the object. If the object is opaque, the light cannot pass through it, and a shadow is formed on the opposite side of the light source. Let's break down this process step-by-step.

1. Light Source: Emits light rays. 2. Object: Blocks some light. 3. Shadow: Forms where light is blocked.

Visual example 1: Shadow creation

light source Shadow

In the figure, we see a light source on the left. It emits light rays in straight lines. When these rays meet an object, some of the light is blocked, and a shadow appears on the other side of the object.

Factors affecting shadow formation

Shadows are not always the same. They can change in size, shape and darkness. Some of the factors that affect shadow formation are:

1. Angle of the light source

The angle at which the light falls on an object determines the size and shape of the shadow. When the light is directly above the object, the shadow is directly below and will be short. When the light is at an angle, the shadow will be long.

2. Distance between the light source and the object

If the light source is closer to the object, the shadow will appear larger because more light is blocked. Conversely, if the light source is farther away, the shadow will appear smaller.

3. Size and shape of the object

The shape of the object will directly translate into the shape of the shadow. A round object will have a round shadow, while an irregularly shaped object will have an irregular shadow. The shape of the object also affects the shape of the shadow.

Types of shadows

Shadows can be classified into different types depending on the area of their formation:

1. Umbra

The umbra is the darkest part of the shadow where all light is blocked. If you are in the umbra, the light source is completely obscured by the object.

2. Penumbra

The penumbra is the lighter part of the shadow, where the light is partially blocked. If you're in the penumbra, only part of the light source is obscured, and you can partially see the light.

Visual example 2: Umbra and penumbra

ghosting Penumbra

In this image, the small black area just behind the object is the umbra, while the larger gray area surrounding it is the penumbra. This shows how these two parts of the shadow look in relation to each other.

Everyday examples of shadow

Shadows are a part of everyday life and observing them can help us learn more about light and objects.

Example 1: A tree in the sunlight

Consider a tree on a sunny day. Sunlight falls on the tree, and the tree casts a shadow on the ground. As the sun moves across the sky, the shadow moves and changes in size and shape.

Example 2: A lamp and a table

When a lamp is placed on a table in a dark room, turning on the light creates shadows under and around the objects on the table. These shadows show how each object is blocking the light.

The importance of shadows in optics

Understanding shadows helps us in a variety of scientific and practical applications, such as:

1. Determining the time

Sundials are ancient devices that tell time using shadows. As the sun moves, the position of the shadow changes, indicating the time of day.

2. Learning about light

By observing shadows, scientists can learn about light intensity, direction, and the properties of light. Shadows help us understand how light interacts with objects.

3. Art creation

Artists use shadows to add depth and dimension to their work. By observing and recreating shadows in their art, they can create more realistic paintings.

Conclusion

The study of shadows provides a clear understanding of the basic principles of light and optics. By understanding how shadows are formed and the factors that influence them, we gain a deeper understanding of the role of light in our world.


Grade 6 → 5.7


U
username
0%
completed in Grade 6

← Prev (5.6)
Lenses and their uses
Next (5.8) →
Dispersion of light and the colour spectrum

Comments 



Creation of shadows

https://www.physicsflow.com/g6/5.7?pfal=en