Class 10 Physics Worksheet Light – Reflection and Refraction

Light is a fascinating phenomenon that plays a crucial role in our daily lives. It helps us see the world around us and enables countless technologies. In Class 10 Physics, “Light: Reflection and Refraction” is a key chapter that lays the foundation for understanding the behavior of light. This worksheet is designed to help students strengthen their concepts and practice important problems related to light.

What is Light?

Light is a form of energy that travels in a straight line as an electromagnetic wave. It does not need a medium to travel and can move through a vacuum, like sunlight traveling through space to reach Earth.

Reflection of Light

Definition: Reflection of light occurs when a ray of light strikes a smooth surface and bounces back into the same medium.

Laws of Reflection

1. The angle of incidence (∠i) is equal to the angle of reflection (∠r).
2. The incident ray, the reflected ray, and the normal (at the point of incidence) all lie in the same plane.

Types of Reflection

1. Regular Reflection: When light reflects from a smooth surface (e.g., a mirror), it forms a clear image.
2. Diffused Reflection: When light reflects from a rough surface, it scatters in different directions, and no clear image is formed.

Important Terms

• Incident Ray: The incoming ray that strikes a surface.
• Reflected Ray: The ray that bounces back after hitting the surface.
• Normal: An imaginary line perpendicular to the surface at the point of incidence.

Reflection in Plane Mirrors

• The image formed by a plane mirror is:
  • Virtual (cannot be captured on a screen)
  • Erect (upright)
  • Same size as the object
  • Laterally inverted (left appears as right and vice versa)

Also Check: CBSE Class 10 Science Chapter 10 Light Reflection and Refraction Notes

Refraction of Light

Definition: Refraction is the bending of light when it passes from one medium to another with a different optical density (e.g., air to water).

Laws of Refraction

1. The incident ray, refracted ray, and the normal all lie in the same plane.
2. The ratio of the sine of the angle of incidence (sin i) to the sine of the angle of refraction (sin r) is constant for two given media. This is known as Snell’s Law:
   $$\frac{\sin i}{\sin r}=\text{constant}=n$$

Key Terms

• Refractive Index ($n$): A measure of how much light bends when entering a medium.
  • Formula:
    $n = \frac{\text{Speed of Light in Vacuum}}{\text{Speed of Light in Medium}}$

    ​

• Critical Angle: The angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90°.
• Total Internal Reflection: Occurs when the angle of incidence exceeds the critical angle, causing light to reflect back entirely into the denser medium.

Effects of Refraction

• Apparent Depth: Objects underwater appear shallower than their actual depth.
• Twinkling of Stars: Caused by the refraction of light through the Earth’s atmosphere.
• Mirage: A natural optical illusion caused by refraction in layers of air with varying temperatures.

Spherical Mirrors

Spherical mirrors are curved mirrors with a polished surface.

Types of Spherical Mirrors

1. Concave Mirror: Reflective surface is on the inside of the curve. It converges light rays.
2. Convex Mirror: Reflective surface is on the outside of the curve. It diverges light rays.

Key Terms for Mirrors

• Pole (P): The center of the mirror’s surface.
• Focus (F): The point where parallel rays converge or appear to diverge after reflection.
• Focal Length ($f$): The distance between the pole and the focus.
• Radius of Curvature ($R$): The distance between the pole and the center of curvature. 

Mirror Formula

$$\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$$

Where:

• 
  $\mathrm{<span\; style="font-family:\; Georgia,\; \text{'}Times\; New\; Roman\text{'},\; \text{'}Bitstream\; Charter\text{'},\; Times,\; serif;">f=\; Focal\; length</span>}$

• 
  $\mathrm{<span\; style="font-family:\; Georgia,\; \text{'}Times\; New\; Roman\text{'},\; \text{'}Bitstream\; Charter\text{'},\; Times,\; serif;"><span\; class="katex"><span\; class="katex-html"\; aria-hidden="true"><span\; class="base"><span\; class="mord\; mathnormal">v</span></span></span></span>\; =\; Image\; distance</span>}$
  $u$

• $u$ = Object distance

Magnification ($m$)

$$m=\frac{\text{Height of Image}}{\text{Height of Object}}=\frac{-v}{u}$$

Lenses

Lenses are transparent objects that refract light to converge or diverge rays.

Types of Lenses

1. Convex Lens: Thicker in the middle, converges light rays, and forms real and virtual images.
2. Concave Lens: Thinner in the middle, diverges light rays, and forms only virtual images.

Lens Formula

$$\frac{1}{f}=\frac{1}{v}-\frac{1}{\mathrm{u<span\; style="font-family:\; Georgia,\; \text{'}Times\; New\; Roman\text{'},\; \text{'}Bitstream\; Charter\text{'},\; Times,\; serif;"></span>}}$$

Magnification for Lenses

$$m=\frac{\text{Height of Image}}{\text{Height of Object}}=\frac{v}{u}$$

 

Also Check: NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction

Worksheet Questions on Reflection and Refraction

Section A: Multiple Choice Questions (MCQs)

1. When light is reflected from a plane mirror, the angle of reflection is:
   • (a) Less than the angle of incidence
   • (b) Equal to the angle of incidence
   • (c) Greater than the angle of incidence
   • (d) Unrelated to the angle of incidence
2. A concave mirror forms a virtual and magnified image when the object is:
   • (a) At the center of curvature
   • (b) Between the focus and the pole
   • (c) At infinity
   • (d) Beyond the center of curvature
3. The speed of light is highest in:
   • (a) Air
   • (b) Water
   • (c) Glass
   • (d) Vacuum
4. A convex lens can form:
   • (a) Only real images
   • (b) Only virtual images
   • (c) Both real and virtual images
   • (d) No image
5. Total internal reflection occurs when light travels from:
   • (a) Air to water
   • (b) Water to glass
   • (c) Glass to air
   • (d) Air to glass

Section B: Short Answer Questions

6. Define the principal focus of a concave mirror.
7. State the two laws of reflection.
8. Why does a concave mirror form a real image?
9. What happens to the speed of light when it passes from air into glass?
10. Differentiate between real and virtual images with examples.
11. Draw a ray diagram to show the image formation in a convex lens when the object is placed at 2F.

Also Check: CBSE Class 10 Science MCQ Chapter 10 Light

Section C: Numerical Problems

12. A ray of light strikes a plane mirror at an angle of 30° with the surface. What is the angle of reflection?
13. A concave mirror has a focal length of 15 cm. If an object is placed at a distance of 10 cm, find the position and nature of the image.
14. The refractive index of water is 1.33. Calculate the speed of light in water. (Speed of light in vacuum =3
    $3 \times 10^8 \, \text{m/s}$

     

15. An object is placed 12 cm from a convex lens with a focal length of 8 cm. Find the position and nature of the image.
16. A glass slab of thickness 6 cm has a refractive index of 1.5. Calculate the lateral displacement of a light ray passing through it.

Section D: Long Answer Questions

17. Explain the phenomenon of refraction with the help of a labeled diagram.
18. Derive the mirror formula for a concave mirror.
19. What is total internal reflection? Explain its applications with two examples.
20. Discuss the formation of a rainbow and the role of refraction in this process.
21. Write the differences between concave and convex lenses based on their properties and applications.

Section E: Ray Diagram Practice

22. Draw ray diagrams for the following situations:

• (a) A concave mirror with the object at infinity.
• (b) A convex lens with the object between F and 2F.
• (c) A concave lens with the object at infinity.

23. Label the following in your diagrams: object position, image position, focal length, and radius of curvature.

Section F: Higher-Order Thinking Skills (HOTS)

24. Why do diamonds sparkle more than ordinary glass? Explain using the concept of total internal reflection.
25. An underwater diver sees the sun at an angle of 45°. Calculate the actual position of the sun in the sky (refractive index of water = 1.33).
26. If the focal length of a concave lens is -20 cm, where will the image form for an object placed 30 cm in front of it?
27. Why do optical fibers use total internal reflection instead of mirrors to transmit light?

Section G: True/False Questions

28. Light travels faster in glass than in air. (True/False)
29. A plane mirror always forms a real image. (True/False)
30. A concave mirror can produce both real and virtual images. (True/False)
31. The critical angle is always measured in the rarer medium. (True/False)
32. The image formed by a convex lens is always inverted. (True/False)

Also Check: NCERT Exemplar Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction

Section H: Fill in the Blanks

33. The distance between the pole and the focus of a spherical mirror is called the ______.
34. The unit of refractive index is ______.
35. The mirror used in vehicle rearview mirrors is a ______ mirror.
36. The bending of light when it passes through a prism is due to ______.
37. The lens that always forms a virtual, erect, and diminished image is a ______ lens.

Section I: Match the Columns