Practice Important Light, Shadows and Reflections Questions for Class 6 Science Exams
FAQs on Light, Shadows and Reflections Worksheets for CBSE Class 6 Science (2025-26)
1. What types of questions are considered important from the chapter Light, Shadows and Reflections for the CBSE Class 6 exam 2025-26?
For the 2025-26 exams, important questions from this chapter typically cover a range of formats to test conceptual understanding. You should focus on:
- Definitions: For key terms like luminous objects, opaque materials, and reflection of light.
- Difference-Based Questions: Questions asking to differentiate between concepts like luminous vs. non-luminous objects, or a shadow vs. an image.
- Conceptual 'Why' Questions: Explaining phenomena, such as why shadows are formed or the working principle of a pinhole camera.
- Application-based Questions: Relating concepts to real-world scenarios and examples.
2. How would you define 'reflection of light'? This is a frequently asked 2-mark question.
Reflection of light is the phenomenon where light rays, after striking a smooth and polished surface, bounce back into the same medium. A plane mirror is an excellent example of a surface that causes regular reflection, which allows us to see our image clearly. For exams, it's important to state that the surface must be smooth and shiny for a clear reflection.
3. What is the difference between a luminous and a non-luminous object? Provide two examples for each.
The key difference lies in their ability to produce their own light. For exam purposes, you can state the differences as follows:
- Luminous Objects: These are objects that have their own light and emit it. Examples include the Sun, a lit bulb, and a firefly.
- Non-luminous Objects: These objects do not produce their own light. They become visible only when they reflect light that falls on them from a luminous source. Examples include the Moon, a chair, and a book.
4. What are the three essential conditions required for the formation of a shadow?
To form a shadow, three things are absolutely necessary, and missing any one of them will prevent a shadow from being cast. These are:
- A source of light (like a torch or the sun).
- An opaque object to block the path of the light.
- A screen or surface behind the object on which the shadow can be formed.
5. Why does a pinhole camera always form an inverted (upside-down) image?
A pinhole camera forms an inverted image because of a fundamental property of light: light travels in straight lines. Light rays from the top of an object travel downwards in a straight line, pass through the tiny pinhole, and strike the bottom of the screen inside the camera. Similarly, rays from the bottom of the object travel upwards, pass through the pinhole, and strike the top of the screen. This crossing of light rays at the pinhole results in a completely inverted image.
6. Why do opaque objects cast dark shadows, while translucent objects cast faint ones?
This difference in shadow intensity is due to how much light each material allows to pass through it.
- Opaque objects, like a wooden block, do not allow any light to pass through them. They create a complete absence of light behind them, resulting in a very dark shadow.
- Translucent objects, like butter paper, allow some light to pass through but scatter it in different directions. Because they only partially block the light, the resulting shadow is much fainter and less defined.
7. How is a shadow fundamentally different from an image formed by a plane mirror?
This is a crucial concept for exams. A shadow and a mirror image are different in several ways:
- Formation: A shadow is formed when light is blocked by an object. An image is formed when light is reflected by a shiny surface.
- Colour: A shadow is always black or grey, irrespective of the object's colour. An image shows the true, vibrant colours of the object.
- Details: A shadow only shows the outline or silhouette of the object. A mirror image shows all the intricate details and textures of the object.
- Inversion: A plane mirror image is laterally inverted (left seems right), while a shadow is a direct projection and is not inverted in this way.
