Reflection and Refraction of Light
Reflection and Refraction of Light
Understanding Reflection
1. Q: What happens to light when it strikes a surface?
Answer: Reflection.
2. Q: What is the difference between regular and diffuse reflection?
Answer: Regular reflection occurs from smooth surfaces, while diffuse reflection occurs from rough surfaces.
Interaction of Light and Objects
3. Q: What are the three things that can happen to light when it strikes an object?
Answer: Reflection, transmission, or absorption.
Terminology
4. Q: What is the incident ray?
Answer: The light ray that strikes the surface.
5. Q: What is the reflected ray?
Answer: The light ray that leaves the surface.
6. Q: What is the normal?
Answer: An imaginary line drawn at right angles to the reflecting surface.
7. Q: What is the angle of incidence?
Answer: The angle between the incident ray and the normal.
Reflection and Refraction of Light
Understanding Reflection
8. Q: What is the angle of reflection?
Answer: The angle between the reflected ray and the normal.
9. Q: What is a plane mirror?
Answer: A mirror with a perfectly flat surface.
10. Q: What is a mirror periscope?
Answer: An instrument that enables an observer to see over an obstacle using mirrors.
11. Q: What are convex mirrors used for?
Answer: They are used in vehicle side-view and rear-view mirrors, and in shops for security purposes.
12. Q: What is an obstacle?
Answer: Something that is in the way.
13. Q: What is a convex mirror?
Answer: A mirror whose reflective surface curves outwards.
The Reflection of Light on Mirrors
Activity 33: Observe Reflection of Light
14. Q: What is the purpose of Activity 33?
Answer: To observe and measure the reflection of light using plane mirrors.
15. Q: What is the significance of the normal in the experiment?
Answer: The normal is a perpendicular line to the mirror's surface, used as a reference point to measure the angles of incidence and reflection.
16. Q: What is the expected observation in the experiment?
Answer: The angle of incidence and the angle of reflection are always equal, regardless of the size of the angle of incidence.
17. Q: What does the term "perpendicular" mean?
Answer: At right angles.
18. Q: What does the term "horizontal" mean?
Answer: Level with the horizon (or the floor).
Refraction of Light
Understanding Refraction
19. Q: What happens to light when it passes from one material to another?
Answer: It changes direction, or bends, which is called refraction.
20. Q: What is the normal in refraction?
Answer: A line drawn at a right angle (90°) to the surface of a material.
21. Q: What is the angle of incidence in refraction?
Answer: The angle between the incident ray and the normal.
22. Q: What is the angle of refraction in refraction?
Answer: The angle between the refracted ray and the normal.
23. Q: What happens to light when it moves from a less dense material to a denser material?
Answer: It is refracted towards the normal.
24. Q: What happens to light when it moves from a denser material to a less dense material?
Answer: It is refracted away from the normal.
25. Q: Why does a pencil appear bent or broken when placed in a glass of water?
Answer: Because of refraction.
Refraction of Light
Activity 34: Show Refraction of Light through a Glass Block
26. Q: What is the purpose of Activity 34?
Answer: To demonstrate how light is refracted through a rectangular glass block.
27. Q: What is the expected observation in Activity 34?
Answer: The incident, refracted, and emergent rays will not be in a straight line, but will be bent due to refraction.
28. Q: Why do the incident, refracted, and emergent rays occur in the observed positions?
Answer: Because light is refracted, or bent, as it passes from one medium (air) to another (glass) and back again.
29. Q: What can be concluded from the observations in Activity 34?
Answer: That refraction occurs when light passes from one medium to another, causing the light to bend.
Refraction of Light
Real and Apparent Depth of an Object Under Water
30. Q: Why does the depth of a water body appear shallower than it really is?
Answer: Due to the refraction of light at the surface of the water.
31. Q: What is the difference between real depth and apparent depth?
Answer: Real depth is the actual distance below the surface of the water to the position of the object, while apparent depth is the distance an object appears to be below the surface of the water when viewed from above.
32. Q: Why does an object in water appear closer to the surface than it really is?
Answer: Because light reflected from the object is refracted away from the normal at the water surface, making the object appear closer to the surface.
Application of Reflection and Refraction
Reflection
33. Q: What are some everyday applications of reflection?
Answer: Security mirrors in shops, torchlights, car headlights, spotlights, searchlights, and lighthouse lights.
34. Q: Why are convex mirrors used as security mirrors in shops?
Answer: Because they produce a smaller image that shows a wide angle view, allowing a large part of the shop to be seen in a single mirror.
35. Q: How do concave mirrors work in torchlights and other light sources?
Answer: The light from the bulb travels towards the mirror, which reflects the light rays and forms a beam of light that can be directed in a particular direction.
Refraction
36. Q: What are some optical instruments that use refraction?
Answer: Hand lenses, microscope lenses, spectacles, cameras, binoculars, and telescopes.
37. Q: How do lenses in spectacles work?
Answer: They use refraction to improve eyesight by bending light rays to focus correctly on the eye.
38. Q: What is the purpose of a camera lens?
Answer: To focus light rays onto a film or electronic image sensor to capture an image.
Activity 35: Revise Reflection and Refraction
Section 1: Reflection
39. Q: Define reflection.
Answer: The change in direction of light when it hits a surface and bounces back.
40. Q: Draw a diagram to show a ray of light striking a smooth surface and being reflected.
Answer: _(Diagram showing incident ray, reflected ray, angles of incidence and reflection)_
41. Q: State the two laws of reflection.
Answer: 1. The incident ray, reflected ray, and normal are all in the same plane. 2. The angle of incidence is equal to the angle of reflection.
42. Q: Give one use of a periscope.
Answer: To see over obstacles, such as in submarines.
43. Q: Give one application of reflection.
Answer: Security mirrors in shops.
Section 2: Refraction
44. Q: Define refraction.
Answer: The bending of light as it passes from one medium to another.
45. Q: Draw a diagram to show a light ray being refracted at the boundary between air and water.
Answer: _(Diagram showing incident ray, normal, refracted ray, angles of incidence and refraction)_
46. Q: Define apparent depth.
Answer: The distance an object appears to be below the surface of the water when viewed from above.
47. Q: Give one application of refraction.
Answer: Lenses in spectacles.
Conclusion and Final Remarks
We have covered a comprehensive range of questions on the topics of Reflection and Refraction of Light. These questions have tested our understanding of the fundamental concepts, laws, and applications of reflection and refraction.
Key Takeaways:
- Reflection: The change in direction of light when it hits a surface and bounces back.
- Refraction: The bending of light as it passes from one medium to another.
- Laws of Reflection: The incident ray, reflected ray, and normal are all in the same plane, and the angle of incidence is equal to the angle of reflection.
- Applications: Mirrors, periscopes, lenses, spectacles, cameras, binoculars, and telescopes.
Final Remarks:
Understanding reflection and refraction is crucial for appreciating the behavior of light and its applications in various fields. These concepts form the basis of many optical instruments and technologies that we use in our daily lives.
We hope that this comprehensive set of questions has helped you reinforce your understanding of reflection and refraction.
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