Spectrum Quiz - ICSE Class 10 Physics

Free practice quiz: Spectrum (ICSE Class 10 Physics). 51 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 10 Physics practice quiz has 51 multiple-choice questions on Spectrum, and 51 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. A prism with an apex angle of 60° is made of glass with a refractive index of 1.5. If a ray of light is incident on one face at an angle of incidence that results in minimum deviation, what is the angle of minimum deviation?

   1. 30°
   2. 37.2°
   3. 45°
   4. 60°
   Show answer

   Answer: B. 37.2°

   For minimum deviation (δm), the angle of incidence (i) equals the angle of emergence (e), and the refracted ray inside the prism is perpendicular to the angle bisector. The formula for minimum deviation is δm = 2i - A, where A is the apex angle. Also, n = sin((A + δm)/2) / sin(A/2). Given A = 60° and n = 1.5, we have 1.5 = sin((60° + δm)/2) / sin(60°/2) = sin((60° + δm)/2) / sin(30°). 1.5 * sin(30°) = 0.75. So, sin((60° + δm)/2) = 0.75. (60° + δm)/2 = arcsin(0.75) ≈ 48.6°. Therefore, 60° + δm ≈ 97.2°, which gives δm ≈ 37.2°.

2. A ray of light passes through a convex lens. If the ray is parallel to the principal axis, after refraction, it will pass through:

   1. The optical center
   2. The principal focus on the other side
   3. The principal focus on the same side
   4. The center of curvature on the other side
   Show answer

   Answer: B. The principal focus on the other side

   One of the principal rules for image formation by a convex lens is that a ray of light passing through the lens parallel to the principal axis, after refraction, converges at the principal focus on the opposite side of the lens.

3. The twinkling of stars is due to:

   1. The absorption of light by the Earth's atmosphere
   2. The reflection of starlight from celestial bodies
   3. The variation in the refractive index of the Earth's atmosphere
   4. The rotation of the Earth
   Show answer

   Answer: C. The variation in the refractive index of the Earth's atmosphere

   The twinkling of stars is caused by the atmospheric refraction. Starlight travels through different layers of the atmosphere which have varying densities and temperatures, leading to fluctuations in the refractive index. This causes the path of light to bend continuously, making the star appear to twinkle.

4. The phenomenon of dispersion of white light by a prism is responsible for:

   1. The formation of a rainbow
   2. The bending of light towards the normal
   3. The scattering of light in the atmosphere
   4. The creation of a virtual image
   Show answer

   Answer: A. The formation of a rainbow

   While dispersion by a prism is the fundamental principle, the formation of a rainbow involves dispersion of sunlight by water droplets in the atmosphere, along with reflection and refraction. The initial splitting of white light into its constituent colors by the prism is the core of dispersion.

5. Which of the following colors of visible light has the longest wavelength?

   1. Violet
   2. Green
   3. Red
   4. Blue
   Show answer

   Answer: C. Red

   The visible spectrum of light consists of colors from violet to red, arranged in the order of increasing wavelength: Violet, Indigo, Blue, Green, Yellow, Orange, Red (VIBGYOR). Red light has the longest wavelength, and violet light has the shortest wavelength.

More questions in this quiz

Answers and explanations are in the full quiz.

1. When white light passes through a glass prism, it splits into its constituent colors. This phenomenon is known as dispersion. Which color deviates the least, and which color deviates the most?
2. A beam of monochromatic light is incident on a right-angled isosceles prism at an angle of incidence such that it suffers total internal reflection at the hypotenuse. If the refractive index of the prism is $\sqrt{2}$, what is the angle of incidence?
3. A convex lens forms an inverted image of a point object. If the object distance is twice the focal length, where is the image formed and what is its nature?
4. When a ray of light passes from a denser medium to a rarer medium, it bends away from the normal. If the angle of incidence in the denser medium is equal to the critical angle, what is the angle of refraction in the rarer medium?
5. A ray of light enters a prism such that the angle of incidence is 40°. The prism has an apex angle of 60° and a refractive index of 1.6. If the ray emerges from the prism at an angle of emergence of 50°, what is the angle of deviation?
6. A lens forms a virtual, erect, and magnified image. This indicates that the lens is a:
7. When light travels from a rarer medium to a denser medium, the speed of light:
8. A concave mirror forms a real, inverted, and magnified image. If the magnification is -3, what is the ratio of the image distance to the object distance?
9. When white light is dispersed by a prism, the different colors are separated due to the variation of the refractive index of the prism material with wavelength. Which of the following statements is correct regarding the refractive indices?
10. A concave lens forms an image of an object placed at a distance of 20 cm from its optical center. The focal length of the lens is 30 cm. What is the nature and position of the image?
11. The phenomenon of scattering of light by tiny particles in the atmosphere is responsible for:
12. When light is incident on a surface, it can be reflected, refracted, or absorbed. The phenomenon of reflection occurs when light:
13. An object is placed at a distance of 15 cm from a convex mirror of focal length 30 cm. What is the nature and position of the image?
14. The color of a clear sky is blue due to which phenomenon?
15. A ray of light is incident on a glass surface at an angle of incidence of 45°. If the refractive index of glass is 1.5, what is the angle of refraction?
16. Which of the following statements is true regarding a concave mirror forming a virtual image?
17. When a ray of light passes from a denser medium to a rarer medium, and the angle of incidence is greater than the critical angle, the phenomenon that occurs is:
18. A convex lens has a focal length of 20 cm. Where should an object be placed to obtain a real, inverted image of the same size as the object?
19. A concave mirror forms a real image at a distance of 30 cm from the mirror. If the object distance is 10 cm, what is the focal length of the mirror?
20. When white light is passed through a prism, it splits into its constituent colors because:
21. An object is placed 10 cm in front of a concave mirror. A virtual, erect, and magnified image is formed at 30 cm in front of the mirror. What is the focal length of the mirror?
22. A lens forms an image where parallel rays incident on it converge to a single point. This point is known as the:
23. What is the phenomenon responsible for the formation of a rainbow?
24. When light travels from a rarer medium to a denser medium, it bends:
25. A convex lens forms an inverted image of size 1/2 of the object. If the focal length of the lens is 20 cm, calculate the object distance.
26. The optical density of a medium is related to its:
27. A ray of light is incident on a plane mirror at an angle of incidence of 30°. The angle of reflection is:
28. When light travels from a denser medium to a rarer medium, the angle of refraction is related to the angle of incidence by Snell's law. If the angle of incidence is less than the critical angle, the ray will:
29. A convex lens forms a real, inverted image that is three times the size of the object. If the focal length of the lens is 10 cm, what is the object distance?
30. Which phenomenon causes the reddish appearance of the sun at sunrise and sunset?
31. When white light passes through a prism, it splits into seven colors. This phenomenon is known as:
32. The critical angle for a pair of media is defined for light traveling from:
33. When light undergoes reflection from a rough surface, the reflected rays are:
34. A ray of light passes through a prism such that the angle of incidence is $i$. The angle of emergence is $e$. The angle of the prism is $A$. The angle of deviation $\delta$ is given by:
35. Which of the following optical phenomena is responsible for the formation of a mirage?
36. A concave lens has a focal length of 15 cm. An object is placed at 30 cm from the optical center. What is the nature and position of the image?
37. A ray of light is incident on a concave mirror at an angle of incidence of 45°. The angle of reflection will be:
38. When light passes from a medium with refractive index $n_1$ to a medium with refractive index $n_2$, and $n_2 > n_1$, the light ray bends:
39. A convex lens forms an inverted image of an object placed at 40 cm from the lens. If the image is formed at 20 cm from the lens, what is the focal length?
40. The splitting of white light into its constituent colors when it passes through a prism is called:
41. A ray of light enters a prism from air and strikes the first face. The angle of incidence is 40°. The angle of refraction inside the prism is 25°. What is the refractive index of the prism material?
42. A convex mirror forms a virtual image at 10 cm behind the mirror. If the object is placed at 20 cm in front of the mirror, what is the focal length?
43. In a prism, the angle between the two refracting surfaces is called the:
44. When a ray of light passes from a denser medium to a rarer medium, it bends away from the normal. This statement is:
45. The phenomenon where light bends as it passes from one medium to another is called:
46. When the object is placed at the center of curvature of a concave mirror, the image formed is:

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