Class 6 Science Chapter 8 Case Based Questions - Light, Shadow and Reflections

Case 1

Sarah is conducting an experiment with different objects to understand the properties of light. She has a wooden box, a glass pane, and a candle. She is using a source of light to observe the behavior of these objects.

Q1: What type of object is the wooden box in this scenario, and why?
Ans: The wooden box is an opaque object because it does not allow light to pass through it.

Q2: If Sarah observes that she can see through the glass pane clearly, what type of object is it, and why?
Ans: The glass pane is a transparent object because it allows light to pass through it clearly.

Q3: How does the behavior of the candle differ from the wooden box and the glass pane in terms of emitting light?
Ans: The candle is a luminous object because it emits its own light.

Q4: Which of the following objects is an example of a translucent object?
(a) Wooden box
(b) Glass pane
(c) Candle
Ans: (b)

Q5: What is the primary characteristic that distinguishes a luminous object from a non-luminous object?
(a) Color
(b) Shape
(c) Ability to emit light
Ans: (c)

Case 2

Mark is using a pinhole camera to capture images. He is experimenting with the camera's focus and understanding the principles behind it.

Q6: Explain how the image formed by Mark's pinhole camera is different from the actual object in terms of size and orientation.
Ans: The image formed by Mark's pinhole camera is inverted and smaller in size compared to the actual object.

Q7: Describe the steps Mark should follow to make a pinhole camera.
Ans: Steps to make a pinhole camera:

• Take two rectangular boxes that fit into one another without any gap.
• Cut open one side of each box.
• Make a small hole in the larger box at the center of the closed end opposite the side that has been cut open.
• Cut a square of side five centimeters in the smaller box in the closed end opposite the side that has been cut open.
• Cover this square with tracing paper.
• Slide the smaller box into the larger box, ensuring that the pinhole and the tracing paper are in line with one another but at opposite ends.
• Slide the smaller box to adjust the focus.

Q8: Why is it mentioned that "the image is not clear" in the context of a pinhole camera?
Ans: The image is not clear because the pinhole camera uses a small hole to form the image, resulting in limited light and reduced clarity.

Q9: What is the principle on which a pinhole camera works?
(a) The principle of reflection of light.
(b) The principle of refraction of light.
(c) The principle of straight-line propagation of light.
Ans: (c)

Q10: Which type of surface reflects the entire light incident on it?
(a) Transparent surface
(b) Opaque surface
(c) Plane mirror surface
Ans: (c)

Case 3

A group of students is discussing the difference between shadows and images. They are using a mirror and a flashlight to observe and learn about these phenomena.

Q11: Explain the similarities and differences between shadows and images.
Ans: Similarities:

• Both shadows and images require a source of light.
• They are formed when light interacts with objects.

Differences:

• Shadows are black and have no color, while images can be colorful.
• Shadows change in length with the position of the sun, while images in a mirror remain the same size.

Q12: Describe the setup and conditions required to observe a shadow and an image.
Ans: To observe a shadow, you need a source of light, an opaque object, and a screen. To observe an image in a mirror, you need a reflective surface and an object in front of it.

Q13: Why do shadows change in length throughout the day, while images in a mirror do not?
Ans: Shadows change in length throughout the day because of the changing angle and position of the sun. Images in a mirror do not change size.

Q14: Which of the following statements is true regarding shadows and images?
(a) Shadows are always colorful.
(b) Images change in size with the position of the sun.
(c) Shadows can be seen without the need for a screen.
Ans: (c)

Q15: What is the main reason behind the formation of shadows?
(a) Reflection of light
(b) Bending of light
(c) Blocking of light
Ans: (b)

Case 4

A group of students is visiting an observatory, where they encounter a two-way mirror. They are curious about its functionality.

Q16: Explain how a two-way mirror works and its practical applications.
Ans: A two-way mirror, also known as a one-way mirror, allows one side to act as a mirror (reflective) and the other side as plain glass (transparent). It is used for observing people without them knowing, such as in police stations or psychological institutions.

Q17: Compare and contrast the behavior of a two-way mirror with a regular plane mirror.
Ans: Comparison with a regular plane mirror:

• A plane mirror is always reflective, whereas a two-way mirror can switch between reflective and transparent properties.

Q18: In what situations might a two-way mirror be used for observation without detection?
Ans: A two-way mirror might be used for covert observation without detection.

Q19: A two-way mirror acts as:
(a) A transparent medium
(b) A translucent medium
(c) A combination of a mirror and plain glass
Ans: (c)

Q20: What type of surface is a smooth plane mirror?
(a) Transparent surface
(b) Opaque surface
(c) Reflective surface
Ans: (c)

Case 5

Tom is studying the concept of reflection and its importance in our daily lives. He is experimenting with various reflective surfaces.

Q21: Explain the concept of reflection of light and how it plays a role in forming images.
Ans: The concept of reflection of light involves the bouncing back of light when it encounters a smooth shiny surface. Reflection plays a role in forming images by redirecting light rays.

Q22: Describe the behavior of light when it is incident on a smooth shiny surface.
Ans: When light is incident on a smooth shiny surface, it reflects back into the same medium following the laws of reflection.

Q23: Provide examples of everyday situations where reflection of light is essential.
Ans: Examples of everyday situations with reflection of light: Mirrors, shiny metal surfaces, glass windows, and still water surfaces.

Q24: Which term best describes the likeness of an object carried and formed by light in a mirror?
(a) Image
(b) Shadow
(c) Reflection
Ans: (a)

Q25: What is the primary characteristic that distinguishes a plane mirror from other reflective surfaces?
(a) Color
(b) Smoothness
(c) Size of reflection
Ans: (b)