Class 7 Science Chapter 11 Light: Shadows and Reflections, introduces students to the basic properties of light. It explains how light travels, how it behaves when it meets different objects, and how images are formed.
Light plays a vital role in our daily life. It enables us to see objects, creates shadows, and allows us to observe reflections in mirrors. Using familiar examples such as the Sun, fireflies, mirrors, shadows, and pinhole cameras, this chapter helps students understand the behavior of light in a simple and practical way. Learning these concepts builds a strong foundation for future studies in optics and helps students relate science to real-life situations.
Shadows and Reflections Worksheet
Our worksheets offer a wide range of practice questions, including MCQs, fill-in-the-blanks, and short and long answer questions. Aligned with the latest curriculum, these worksheets promote critical thinking through concept-based activities, simple experiments, and real-life applications.
With engaging and well-structured content, our worksheets help students strengthen their understanding of classroom concepts, prepare effectively for examinations, and build a strong foundation in science.
Through simple observations and activities, this chapter helps us understand:
- How light is produced and the difference between luminous and non-luminous objects
- That light travels in a straight line and how this property can be proved using simple experiments
- How different materials (transparent, translucent, and opaque) affect the passage of light
- How shadows are formed, the conditions required for shadow formation, and factors that affect their size and shape
- The meaning of reflection of light and how mirrors change the direction of light
- The characteristics of images formed by a plane mirror, including erect image, same size, and lateral inversion
This chapter builds a strong conceptual foundation in optics, develops scientific observation skills, and prepares students for more advanced topics related to light in higher classes.
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Science Class 7 chapter 11 Study Notes
Sources of Light
- Luminous objects: Objects that emit their own light (Sun, stars, fire, fireflies).
- Non-luminous objects: Objects that do not emit light and are seen by reflected light (Moon, planets, books).
- The Moon shines because it reflects sunlight, not because it produces light.
Does Light Travel in a Straight Line?
- Light travels in a straight line.
- Experiments with aligned matchboxes, straight pipes, and laser beams confirm this property.
- Light cannot bend around corners under normal conditions.
Transparent, Translucent, and Opaque Materials
- Transparent: Allow light to pass almost completely (glass, clean water).
- Translucent: Allow light to pass partially (tracing paper, frosted glass).
- Opaque: Do not allow light to pass (wood, cardboard).
Shadow Formation
A shadow is formed when light is blocked by an object.
Requirements for shadow formation:
- Source of light
- Opaque object
- Screen (wall, floor, ground)
- Opaque objects form dark shadows.
- Translucent objects form lighter shadows.
- Colour of the object does not affect shadow colour.
- Shadow size depends on the distance between:
- light source and object
- object and screen
Reflection of Light
- Reflection is the change in direction of light when it strikes a shiny surface or mirror.
- Mirrors can redirect sunlight and form bright spots.
- Reflection enables us to see images in mirrors.
Images Formed by a Plane Mirror
Characteristics:
- Image is erect
- Image is same size as the object
- Image cannot be obtained on a screen
- Image shows lateral inversion (left-right reversal)
- Image appears at the same distance behind the mirror as the object is in front
Useful Devices Based on Reflection
- Periscope: Uses two plane mirrors to see objects not in direct view.
- Kaleidoscope: Uses multiple reflections to create colourful patterns.
Light: Shadows and Reflections Question Answers
Q1. What is a luminous object?
Ans. A luminous object is an object that produces or emits its own light. Such objects do not need any other source of light to be seen. They are the original sources of light.
Examples of luminous objects include the Sun, stars, burning candle, electric bulb, fire, and fireflies. The Sun is the main natural source of light on the Earth and helps us see all other objects around us.
Q2. Why is the Moon called a non-luminous object?
Ans. The Moon is called a non-luminous object because it does not produce its own light. It appears bright at night because it reflects the light of the Sun that falls on its surface. Since the Moon only reflects light and does not emit light on its own, it is classified as a non-luminous object.
Q3. How can you show that light travels in a straight line?
Ans. Light travels in a straight line, and this can be shown using a simple experiment.
If three matchboxes with holes are placed in a straight line and a torch is kept at one end, light passes through all the holes and reaches a screen. When one matchbox is moved slightly, the light does not reach the screen.
This shows that light cannot bend around obstacles and always travels in a straight path.