NCERT Solutions for Class 8 Science Chapter 16 Light

The chapter “Light” in Class 8 Science (Chapter 16) is one of the most important topics in the CBSE Class 8 Science syllabus. It forms the foundation of optics, explaining how light enables us to see objects, how it reflects, refracts, and how mirrors and lenses work in daily life. Understanding this chapter helps students build strong conceptual clarity for higher classes, especially for physics chapters in Class 9 and 10.

This page provides detailed, step-by-step NCERT Solutions for Class 8 Science Chapter 16 – Light, covering all in-text and exercise questions from the textbook. Each answer is explained in simple language to help students understand concepts clearly and score better marks.

Whether students want to revise before exams or clarifying your doubts, this comprehensive guide on NCERT Solutions for Class 8 Science Chapter Light is designed to be the only resource you’ll need to master the chapter.

Download NCERT Solutions for Class 8 Science Chapter 16 Light (Free PDF)

Download the complete NCERT Solutions for Class 8 Science Chapter 16 – Light (PDF) that includes all exercise questions and answers from the NCERT textbook.
This free, easy-to-access file is ideal for offline study, allowing students to revise concepts, practice numerical questions, and strengthen their understanding of the Light chapter anytime, anywhere.

Class 8 Science Chapter 16 Light: Important Topics

The chapter “Light” in Class 8 Science explains how light enables vision, reflection, image formation, and the structure of the human eye. Below is a quick revision summary of all major concepts to help students recall the chapter easily before exams.
These Class 8 Science Light notes also support quick conceptual revision for NCERT-based tests and Olympiads.

Light Class 8 Key Concepts and Definitions

NCERT Solutions for Class 8 Science Chapter 16 Light (All Exercise Questions)

The following are NCERT Solutions for Class 8 Science Chapter 16 – Light, explained in simple, exam-oriented language. Each answer is written as per the latest NCERT guidelines, helping students clear their doubts and strengthen concepts related to reflection, human eye, kaleidoscope, and vision defects.

Light Class 8 MCQs (Multiple Choice Questions) with Answers

Solve Light Class 8 MCQs by marking the correct option and give a brief, exam-style explanation (concept first, then reason).

The law “∠i = ∠r” refers to:

A) Refraction 

B) Reflection 

C) Dispersion 

D) Diffraction

Ans: B. In reflection, the angle of incidence equals the angle of reflection; rays and normal lie in one plane.

Image in a plane mirror is:

A) Real, inverted 

B) Diminished 

C) Virtual, laterally inverted, same size 

D) Magnified

Ans: C. Plane mirrors produce virtual, upright, laterally inverted images of equal size.

Regular reflection occurs from:

A) Rough wall 

B) Paper 

C) Polished mirror 

D) Chalk powder

Ans: C. Smooth surfaces reflect parallel rays in parallel, giving clear images.

Diffused reflection happens because:

A) Laws of reflection fail 

B) Surface irregularities scatter rays 

C) Light speed changes 

D) Absorption only

Ans: B. Both types still obey the laws; roughness causes scattering.

The part of eye that controls light entry (aperture) is:

A) Retina 

B) Pupil 

C) Lens 

D) Optic nerve

Ans: B. Iris regulates pupil size to adjust incoming light; image forms on retina.

Cells sensitive to dim light are:

A) Rods 

B) Cones 

C) Bipolar cells 

D) Ganglion cells

Ans: A. Rods work in low light; cones for bright light and colour vision.

Braille is used by:

A) Colour-blind persons 

B) Visually impaired persons 

C) Hearing impaired 

D) Dyslexic learners

Ans: B. Braille is a tactile script read by touch (raised dots).

Kaleidoscope works on:

A) Refraction 

B) Multiple reflections 

C) Diffraction 

D) Interference

Ans: B. Mirrors at angles produce repeated symmetric patterns.

White light splits into colours in a prism because of:

A) Reflection 

B) Scattering 

C) Dispersion (wavelength-dependent refraction) 

D) Polarisation

Ans: C. Each colour bends differently; order is V-I-B-G-Y-O-R.

The colour band from violet to red is called:

A) Spectrum (VIBGYOR) 

B) Monochrome 

C) Filter 

D) Shadow

Ans: A. Prism dispersion produces a continuous spectrum.

Which is true for diffused reflection?

A) ∠i ≠ ∠r 

B) Rays reflect in many directions due to roughness 

C) No image can ever form 

D) Laws fail

Ans: B. Scatter occurs but laws still hold at each point.

Blind spot means:

A) Retina richest in cones 

B) No photoreceptors; optic nerve leaves eye 

C) Lens defect 

D) Cataract region

Ans: B. No rods or cones present, hence no image detection.

Lateral inversion means:

A) Top–bottom swap 

B) Left–right reversal in mirror image 

C) Front–back swap 

D) Rotation of object

Ans: B. Characteristic of plane mirror images.

In a dark room, reading is difficult mainly because:

A) Lens absent 

B) Cones require bright light 

C) Rods non-functional 

D) Iris closed

Ans: B. Cones support colour/detail in bright light; rods handle dim vision.

Which statement about rainbow is correct?

A) Pure reflection only 

B) Combination of refraction, dispersion, and internal reflection 

C) Only diffraction 

D) Polarisation only

Ans: B. Sunlight disperses and internally reflects in raindrops to form a spectrum arc.

NCERT Solutions for Class 8 Science Chapter 13 Light Questions and Answers (Short & Very Short)

What is reflection of light Class 8?

Answer: Reflection of light is the phenomenon by which a ray of light falling on a surface bounces back into the same medium. For example, when a beam of light strikes a mirror, it is reflected off the mirror surface. In simple terms: Light hits a surface + comes back = reflection.

What are the 2 laws of reflection?

Answer:

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

What is the difference between Regular and Diffused Reflection?

Answer:

What is dispersion of light?

Answer: Dispersion of light is the process by which white light splits into its component colours when passing through a transparent medium like a prism. For example, when sunlight passes through a triangular glass prism, it separates into red, orange, yellow, green, blue, indigo and violet (VIBGYOR).
A natural example is a rainbow, where water droplets act like prisms and disperse sunlight.

What is a ray of light?

Answer: A ray of light is an imaginary line that represents the path along which light energy travels. It starts at the source and goes in one direction. In diagrams, it is shown as a straight arrow pointing away from the source.

What is the normal in light reflection?

Answer: The normal is an imaginary line drawn perpendicular (90°) to the reflecting surface at the point of incidence (where the incident ray strikes). It helps measure the angles of incidence and reflection.

Why does a mirror form a virtual image?

Answer: A plane mirror forms a virtual image because the reflected rays appear to diverge from a point behind the mirror; no real light rays converge at that point. The image is upright and of the same size as the object, but laterally inverted.

What happens to a beam of light in regular reflection?

Answer: In regular reflection, when a parallel beam of light rays falls on a smooth and polished surface, the rays are reflected in parallel. Because of this, a clear and sharp image is produced.

What happens to a beam of light in diffused reflection?

Answer: In diffused reflection, when a parallel beam of light falls on a rough surface, the rays reflect in many directions, because the tiny irregularities cause scattering. Thus no clear image is formed.

What is the spectrum of white light?

Answer: The spectrum of white light refers to its constituent colours (red, orange, yellow, green, blue, indigo, violet) as seen when white light is dispersed (for example, by a prism or water droplets). The order is typically red (least deviation) to violet (most deviation).

What is a prism?

Answer: A prism is a transparent optical element, usually with triangular cross-section, that can refract and disperse white light into its component colours. It causes different wavelengths to bend by different amounts, thereby splitting the light.

What is the cause of dispersion of light through a prism?

Answer: Dispersion occurs because different colours (wavelengths) of light travel at different speeds in a medium and thus refract by different amounts. For example, violet bends more than red when passing through a prism.

What is a rainbow?

Answer: A rainbow is a natural optical phenomenon in which sunlight is refracted, internally reflected, and dispersed by many tiny water droplets in the atmosphere, forming a multi-coloured circular arc (order: red outside, violet inside).

What is the human eye?

Answer: The human eye is a sense organ that detects light and produces images. It has parts such as the cornea, iris, pupil, lens, retina (with rods and cones) and optic nerve. It helps us see by focusing light and converting it into nerve signals sent to the brain.

What are rods and cones?

Answer: Rods and cones are the two types of photoreceptor cells found in the retina of the human eye.

• Rods: sensitive to dim light, enable night vision but don’t detect colours.
• Cones: active in bright light, enable colour vision and sharp detail.

Access Answers to NCERT Class 8 Science Chapter 16 Light

Question 1: Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room? Explain.

Answer:
No, we cannot see objects in a dark room because there is no light falling on them. The human eye can perceive an object only when light from that object enters our eyes. If the room is dark, the objects do not reflect any light; hence, they are invisible to us.

However, if there is light outside the room, objects outside can be seen through a window or door because light from those objects enters our eyes.

Question 2: Differentiate between regular and diffused reflection. Does diffused reflection mean the failure of the laws of reflection?

 Diffused reflection does not mean failure of the laws of reflection. Each individual ray still obeys the laws of reflection, but due to the irregular surface, the reflected rays are not parallel and get scattered.

Question 3: State the laws of reflection. Answer:
The laws of reflection of light are as follows:

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

Diagram: Laws of Reflection (Image Credit: Shutterstock)

Question 4: Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.

Answer: Activity Steps:

1. Take a plane mirror, a sheet of paper, and a drawing board.
2. Fix the paper on the board using pins and place the mirror vertically along one edge.
3. Draw a normal line and an incident ray on the paper.
4. Place two pins on the incident ray (P₁ and P₂).
5. Observe the reflected ray and place two pins (P₃ and P₄) along its direction.
6. Remove the mirror and fold the paper along the mirror line.
7. You’ll notice that the incident ray, reflected ray, and the normal all lie on the same plane (the paper surface).

This confirms the second law of reflection experimentally.

Question 5. Fill in the blanks.

(a) The angle of incidence is equal to the angle of reflection. 

Answer: Angle of incidence = Angle of reflection. 

(b) The image formed by a plane mirror is ____ and ____. 

Answer:Virtual and erect. 

(c) The radius of curvature of a plane mirror is ____. 

Answer:Infinite. 

(d) An image that cannot be obtained on a screen is called a ____ image. 

Answer:Virtual image. 

(e) The mirror used by dentists to see the enlarged image of teeth is a ____ mirror. 

Answer:Concave mirror. 

(f) The rear-view mirror of a car is a ____ mirror. 

Answer:Convex mirror.

Question 6: The angle of incidence is equal to the angle of reflection. 

(a) Always 

(b) Sometimes 

(c) Under special conditions 

(d) Never

Correct Answer: (a) Always This is the first law of reflection. It applies to all reflecting surfaces, whether smooth or rough. Each reflected ray individually obeys the law.

Question 7: Describe the construction of a kaleidoscope.

Answer: A kaleidoscope is an optical device that produces beautiful symmetrical patterns by multiple reflections of light. Construction Steps:

1. Take three rectangular mirrors of equal size and join them to form a triangular prism.
2. Fix the prism inside a cylindrical cardboard tube.
3. Cover one end with a transparent glass sheet, and the other with a translucent paper.
4. Place small colored glass pieces or beads between the mirrors and the glass plate.
5. When viewed through the open end, repeated reflections create stunning patterns.

Uses: Kaleidoscopes are used in designing, textile work, and to demonstrate the principle of multiple reflection.

Question 8: Draw a labelled sketch of the human eye.

Answer:
The human eye works like a natural optical instrument that focuses light on the retina for vision. Key Parts: Cornea, Iris, Pupil, Lens, Retina, Optic Nerve, Ciliary Muscles, Aqueous Humor, Vitreous Humor. Diagram: Human Eye (Labelled)

Question 9: Gurpreet wanted to perform Activity 16.8 using a plane mirror, a screen and a candle flame. Explain what she should observe.

Answer:
When Gurpreet places a candle in front of a plane mirror, she observes a virtual image of the flame behind the mirror.

• The image appears as far behind the mirror as the object is in front.
• It is upright, of the same size, and laterally inverted.
  This confirms that plane mirrors form virtual and erect images following the laws of reflection.

Question 10: Explain how you can take care of your eyes.

Answer:
To keep the eyes healthy and maintain good vision:

• Always read or write in proper light (not too dim or bright).
• Take regular breaks when using screens or reading for long periods.
• Eat a diet rich in Vitamin A (carrots, spinach, milk).
• Avoid staring at bright light sources directly.
• Keep eyes clean and avoid touching them with unwashed hands.
• Get regular eye check-ups if you experience blurred vision or discomfort.

Maintaining good eye hygiene ensures better focus and long-term visual health.

Question 11: Gurpreet wanted to perform Activity 16.8 using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teacher's advice?

Answer:

The teacher's advice is a very important safety warning. It is extremely dangerous to look directly at a laser beam.

Here's why:

• High Intensity: A laser is not like a regular torch. Its light is very, very intense and concentrated.
• Retina Damage: This high-intensity light can permanently damage the retina (the light-sensitive screen at the back of your eye).
• Blindness: This damage can happen in an instant and can lead to permanent loss of vision or blindness.

The teacher advised Gurpreet not to use the laser to protect her eyes from severe and permanent damage.

Question 12: Explain how you can take care of your eyes.

Answer:

Our eyes are precious, and taking care of them is very important. Here are some key ways to maintain good eye health:

• Proper Light: Always read or study in sufficient light. Reading in light that is too dim or too bright can cause eye strain and headaches.
• Never Look at the Sun: Never look directly at the sun or any other very powerful light source. The intense rays can permanently damage your retina.
• Wash Your Eyes: Wash your eyes frequently with clean water. This helps remove any dust or particles.
• Maintain Reading Distance: Always read at the least distance of distinct vision, which is about 25 cm. Don't hold the book too close to your eyes or keep it too far.
• Take Breaks: If you use a computer, tablet, or phone for a long time, take short breaks every 20-30 minutes. Look away from the screen and blink several times to rest your eyes.
• Eat a Healthy Diet: A balanced diet is essential. A deficiency of Vitamin A can cause eye problems like night blindness. Include foods rich in Vitamin A, like carrots, spinach, leafy greens, and eggs, in your diet.

 Question 13: What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?

Answer:

Given: The total angle between the incident ray and the reflected ray is 90°.

Concept: The Law of Reflection states: Angle of Incidence (i) = Angle of Reflection (r).

Solution: The total angle is i + r. So, i + r = 90°. Since i = r, we can write i + i = 90°, or 2i = 90°. Therefore, i = 45°.

Final Answer: The angle of incidence is 45°.

Question 14: How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?

Answer:

An infinite number of images will be formed.

• Concept: This happens because of multiple reflections.
• Explanation: When two plane mirrors are parallel, the image formed by the first mirror acts as a virtual object for the second mirror. The second mirror then forms an image of that virtual object.
• This new image then acts as a new object for the first mirror, and this process repeats back and forth forever, creating a long line of reflections.
• (Note: The 40 cm distance is extra information. The distance between the mirrors affects how far apart the images appear, but not the total number of images formed.)

 Question 15: Two mirrors meet at right angles (90°). A ray of light is incident on one at an angle of 30° as shown. Draw the reflected ray from the second mirror.

Answer:

We apply the Law of Reflection twice:
1. First Mirror (Vertical): The angle of incidence (i1) is 30°. So, the angle of reflection (r1) is also 30°.

2. Second Mirror (Horizontal): Using geometry, the ray from the first mirror hits the second mirror at an angle of 60° (90° - 30° = 60°). This is the new angle of incidence (i2).
3. Final Reflection: Since i2 = 60°, the final angle of reflection (r2) from the second mirror is also 60°.

Question 16: Boojho stands at A just on the side of a plane mirror. Can he see himself in the mirror? Also can he see the image of objects situated at P, Q and R?

Answer:

This question is about the "field of view" of a plane mirror.

• (a) Can Boojho see himself?
  • No, Boojho cannot see himself. To see his own reflection, light from his body must strike the mirror and reflect back to his eyes. Since he is standing off to the side, the light from his body that hits the mirror will reflect away from his eyes.

• (b) Can he see objects at P, Q, and R?
  • An object is visible if the light from it can hit the mirror and reflect into Boojho's eyes (at position A).
  • Image of P: Yes, he can see P. A ray of light from P can strike the mirror and reflect to position A.
  • Image of Q: Yes, he can see Q. A ray of light from Q can strike the mirror at a point and reflect to position A.
  • Image of R: No, he cannot see R. The object R is too far to the side. Any light from R that hits the mirror will reflect away from Boojho and will not reach his eyes at position A.

Question 17: (a) Find out the position of the image of an object situated at A in the plane mirror. (b) Can Paheli at B see this image? (c) Can Boojho at C see this image? (d) When Paheli moves from B to C, where does the image of A move?

Answer:

• (a) Position of the Image: The image of object A will be formed behind the plane mirror. It will be at the same perpendicular distance from the mirror as A is in front of it. This image is virtual and erect. Let's call the image A'.
• (b) Can Paheli at B see this image?
  • Yes, Paheli can see the image. Light rays from A hit the mirror and reflect; these reflected rays appear to come from the image A'. A ray from A can reflect to Paheli's eye at B.
• (c) Can Boojho at C see this image?
  • Yes, Boojho can also see the image. Just like with Paheli, a reflected ray from A can reach Boojho's eye at C.
• (d) When Paheli moves from B to C, where does the image of A move?
  • The image does not move at all. The position of an image in a plane mirror depends only on the position of the object (A) and the position of the mirror. It does not matter where the observer (Paheli or Boojho) is standing. The image A' will remain fixed in its position.

Light Class 8 Extra Questions and Answers (Important)

The chapter “Light” in Class 8 Science explains fundamental optical concepts such as reflection, refraction, the human eye, and the Braille system. Beyond NCERT solutions, students should practise extra and important questions for class 8 light that often appear in exams and competitive assessments.

What is Lateral Inversion?

Lateral inversion is the phenomenon in which the left and right sides of an image appear interchanged when seen in a plane mirror. For example, when the word “AMBULANCE” is written in reverse on emergency vehicles, the mirror in front of a driver’s car shows it correctly oriented. This happens because mirrors reverse the image sideways, not top to bottom. In simple terms: The left side of the object appears as the right side in the mirror image, and vice versa. This concept demonstrates how mirrors follow the laws of reflection while altering perceived orientation—an essential idea in optics and daily life applications.

What is the Difference Between Rods and Cones?

Rods and cones are two types of photoreceptor cells in the retina of the human eye. Both help in vision, but they perform distinct functions.

Key takeaway: Rods enable night vision, while cones provide colour and detail during daylight.

What is the Blind Spot in the Eye?

The blind spot is the point on the retina where the optic nerve exits the eye. At this spot, no rods or cones are present, so no image is formed when light falls on it. Even though each eye has a blind spot, humans usually don’t notice it because the visual fields of both eyes overlap, and the brain fills in the missing information. In short: The blind spot is a natural gap in the retina where the optic nerve leaves the eyeball, resulting in the absence of photoreceptor cells. This concept illustrates how the structure of the human eye affects vision.

Explain the Braille System

The Braille System is a tactile writing method used by visually impaired individuals to read and write through the sense of touch. It was invented by Louis Braille in the 19th century. Each Braille character is made up of a pattern of six raised dots, arranged in a 3×2 cell. Different combinations of dots represent letters, numbers, and punctuation marks. Braille allows reading by feeling the raised patterns with fingertips and writing using a stylus or Braille typewriter. In Class 8 Science, the Braille system is discussed as an example of how humans adapt technology to overcome visual limitations—demonstrating the link between light, vision, and sensory substitution.

NCERT Soltuions for Class 8: Solved Numericals for Class 8 Light

To score full marks, you must practice the light class 8 numericals. These problems mainly test your understanding of the laws of reflection and the properties of plane mirrors. Below are 8 important solved questions with detailed, step-by-step answers.

Question: An incident ray strikes a plane mirror such that the angle of incidence is 35°. What will be the angle of reflection?

Answer:

Given: The angle of incidence (i) = 35°

To Find: The angle of reflection (r)

Concept (Formula): This problem is based on the First Law of Reflection, which states: Angle i = Angle r.

Solution: We are given i = 35°. According to the law, r = i. Therefore, r = 35°.

Final Answer: The angle of reflection will be 35°.

Question: A ray of light strikes a plane mirror at an angle of 25° with the mirror surface. What will be the angle of reflection?

Answer:

Given: Angle with the mirror surface = 25°.

To Find: The angle of reflection (r).

Concept (Formula): This is a trick question. The angle of incidence (i) is the angle with the normal (90° line), not the mirror.

Step 1: Find i: i = 90° - (Angle with mirror) = 90° - 25° = 65°.

Step 2: Use Law of Reflection: r = i.

Solution: Since i = 65°, then r = 65°.

Final Answer: The angle of reflection will be 65°.

Question: If the angle of reflection for a ray of light is 50°, what is the total angle between the incident ray and the reflected ray?

Answer:

Given: r = 50°

To Find: Total angle between incident and reflected ray.

Concept (Formula): Total Angle = i + r. By the Law of Reflection, i = r.

Solution: Since r = 50°, then i = 50°. Total Angle = 50° + 50° = 100°.

Final Answer: The total angle is 100°.

Question: Sonia is standing 5 meters in front of a large plane mirror. What is the distance between Sonia and her image?

Answer:

Given: Object distance = 5 m.

To Find: Distance between object (Sonia) and her image.

Concept (Formula): In a plane mirror, Image Distance = Object Distance. The total distance = (Object Distance) + (Image Distance).

Solution: Image Distance = 5 m. Total Distance = 5 m + 5 m = 10 m.

Final Answer: The distance between Sonia and her image is 10 meters.

Question: Two plane mirrors are placed perpendicular to each other (at an angle of 90°). If an object is placed between them, how many images will be formed?

Answer:

Given: Angle (θ) = 90°

To Find: Number of images (n).

Concept (Formula): n = (360° / θ) - 1 (when 360/θ is an even integer).

Solution: First, calculate m = 360° / 90° = 4. Since 4 is an even integer, we use the formula: n = 4 - 1 = 3.

Final Answer: 3 images will be formed.

Question: A kaleidoscope uses three mirrors inclined at 60° to each other. How many images are formed by two of those mirrors (inclined at 60°)?

Answer:

Given: Angle (θ) = 60°

To Find: Number of images (n).

Concept (Formula): n = (360° / θ) - 1.

Solution: First, calculate m = 360° / 60° = 6. Using the formula: n = 6 - 1 = 5.

Final Answer: 5 images will be formed.

Question: A boy is in a barber's shop where two mirrors are placed parallel to each other. How many images of the boy will be formed?

Answer:

Given: Mirrors are parallel (Angle θ = 0°).

To Find: Number of images (n).

Concept (Formula): When mirrors are parallel, light reflects back and forth infinitely. The formula 360° / 0° is undefined, or infinity (∞).

Solution: The image in one mirror acts as an object for the other, repeating forever.

Final Answer: An infinite (∞) number of images will be formed.

Question: A person is standing 3 meters from a plane mirror. If the person moves 1 meter backwards (away from the mirror), what will be the new distance between the person and their image?

Answer:

Given: Initial distance = 3 m. Person moves 1 m back.

To Find: New total distance between person and image.

Concept (Formula): Total Distance = (New Object Distance) + (New Image Distance).

Solution: New Object Distance = 3 m + 1 m = 4 m. New Image Distance = New Object Distance = 4 m. Total Distance = 4 m + 4 m = 8 m.

Final Answer: The new distance will be 8 meters.