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Class 8 Science Chapter 10 Light Mirrors and Lenses Extra Questions
Class 8 Science Chapter 10 Extra Questions on Light Mirrors and Lenses
Light Mirrors and Lenses Class 8 Very Short Question Answer
Question 1.
Why does a mirror reverse the word “LEFT” to “TFEL”?
Answer:
Lateral inversion swaps left and right in mirror reflections.
Question 2.
What type of lens is used in magnifying glasses?
Answer:
A magnifying glass uses a convex lens.
Question 3.
State the two laws of reflection of light.
Answer:
First Law : The incident ray, the reflected ray, and the normal to the surface all lie in the same plane.
Second Law : The angle of incidence is equal to the angle of reflection. (∠r = ∠r )
Question 4.
Why are convex mirrors used as rear-view mirrors in vehicles instead of plane or concave mirrors?
Answer:
Convex mirrors are best for rear-view mirrors because they provide a wide, upright, and clear image, enhancing road safety.
Question 5.
A boy is standing in front of a plane mirror. He lifts his right hand. Which hand appears to be raised in the mirror image?
Answer:
The left hand appears to be raised in the mirror image.
Question 6.
Give one daily-life example where lateral inversion is noticeable.
Answer:
The mirror reverses the image left to right, so the text appears flipped, making it hard to read in the mirror.
Question 7.
Why is a convex mirror preferred in security mirrors?
Answer:
Convex mirrors are used in security mirrors because they provide a wider view, form erect images, and help monitor large areas efficiently.
Question 8.
What happens to the word “MIRROR” when reflected in a plane mirror?
Answer:
RORRIM
Question 9.
Why can’t we see our image in a piece of paper, even though it reflects some light?
Answer:
Paper’s surface is rough, so it scatters light in all directions – no clear reflection.
Question 10.
Can an image formed by a plane mirror be projected on a screen?
Answer:
No, a plane mirror forms a virtual image.
Light Mirrors and Lenses Class 8 Short Question Answer
Question 1.
Why does a convex lens converge light rays while a concave lens diverges them?
Answer:
A convex lens is thicker at the centre than at the edge, so it bends rays inward. A concave lens is thinner at the centre and does the opposite by bending rays outward.
Question 2.
Give two uses of plane mirrors in daily life.
Answer:
Dressing mirrors : Used in bedrooms and bathrooms for personal grooming and checking appearance.
Interior rear-view mirror in cars To see traffic behind you.
Question 3.
Look at figure. Can the image of the child in it be Obtained on a screen? (Competency Based Que.)
Answer:
The image of the child cannot be obtained on the screen because the image is not real. The images formed by plane mirror are virtual, so these virtual images cannot be seen on the screen.
Question 4.
Draw figure showing the position of the plane mirror. Also, label the angle of incidence and angle of reflection on it. (NCERT Exemplar)
Answer:
x = Angle of incidence
y = Angle of reflection
Question 5.
“The laws of reflection only holds true for regular reflection”. Is this statement true or false? Explain your answer.
Answer:
False, the laws of reflection holds for both regular and diffused reflection. In a diffused reflection, the reflecting surface being rough and uneven, the parallel beam of light is reflected in different directions and angles.
Question 6.
How does a concave mirror differ from a convex mirror in terms of reflecting light?
Answer:
A concave mirror causes parallel rays to meet at a spot in front of the mirror, allowing real images to form. A convex mirror makes rays spread outward as if coming from behind it, producing only virtual, smaller images.
Question 7.
Hold a spoon and look at your reflection on both sides. What do you observe? What kind of mirror do the two sides represent? (Competency Based Que.)
Answer:
When you look at the outer (back) side of the mirror which is convex, you see a smaller upright, wide angle image. In contrast when you look at the inner (hollow) side of the mirror, which is concave, you see a magnified close-up image when the object is close or an inverted image when it is farther away.
Question 8.
Imagine a torch is used to shine light on a mirror in a dark room. Describe what will happen to the light and how the mirror helps.
Answer:
When light from a torch falls on a mirror in a dark room, the mirror reflects the light according to the law of reflection and redirects its heeping illuminate another part of the room.
Question 9.
Why is the image formed by a plane mirror said to be virtual and erect?
Answer:
Virtual : Reflected rays diverge, they only seem to meet behind the mirror, so no real light passes through the image.
Erect : The top and bottom of the image remain in the same orientation as the object, so it appears upright.
Light Mirrors and Lenses Class 8 Long Question Answer
Question 1.
There is a mistake in each of the following ray diagrams given as figure (a), (b), and (c). Make the necessary correction(s). (Competency Based Que.)
Answer:
The correct diagrams are as below
Question 2.
Draw a labelled ray diagram showing the reflection of light from a plane mirror.
Answer:
Question 3.
Explain why the word “AMBULANCE” is written laterally inverted on hospital vAnswer:
Answer:
The word “AMBULANCE” is painted in reverse on the front of the van so that drivers see it correctly in their rear-view mirrors. A plane mirror laterally inverts whatever it reflects, so the flipped “ECNALUBMA” on the vehicle appears as the normal “AMBULANCE” in your mirror-letting you read it instantly and give way to the emergency vehicle.
Question 4.
Figure shows the word REST written in two ways in front of a mirror. Show how the word would appear in the mirror? (Competency Based Que.)
Answer:
According to reflection properties of plane mirror, it forms same size, laterally inverted images of the object infront of them.
Question 5.
A child claims that the image formed by a mirror is smaller than the object. Which type of mirror might the child be referring to? Justify your answer.
Answer:
The child is most likely referring to a convex mirror, because
(i) Convex mirrors always produce virtual, upright and diminished images (smaller than the object).
(ii) Their outward-curved surface diverges incoming rays, so the reflected rays appear to originate from a point behind the mirror, forming a reduced image.
Light Mirrors and Lenses Class 8 Case Based Questions
Question 1.
The picture shows a light ray from a candle falling on a mirror. P, Q, R, S and Tare five points behind the mirror.
Answer the following questions based on the above information.
(i) Which arrow represents the light ray reflected by the mirror?
(a) Arrow 1
(b) Arrow 2
(c) Arrow 3
(d) Arrow 4
(ii) At which point, will the image of the candle form? Will the image be erect or inverted ?
(iii) Which of these statements is true for reflection of light rays? Choose ‘Yes’ or ‘No’ for the correct response.
| Is the statement true? | Yes or No |
| (a) Light rays are reflected by plane surfaces only. | Yes/No |
| (b) Angle of incidence is equal to the angle of reflection | Yes/No |
| (c) Incident ray and reflected ray meet at the same point. | Yes/No |
Answer
1. (i) (c) Arrow 2 is normal to the mirror. Hence, by measuring angle between incident ray and arrow 2, the reflected ray will be arrow 3. Option (c) is correct.
(ii) Extend the arrow 3 behind the mirror. It will meet to Q. Hence, image will be formed at Q. Plane mirror always forms the image in the . same orientation as the object. Since, the object is erect, hence the image will also be erect.
(iii) (a) No, (b) Yes, (c) Yes.
Skill Based Questions
Question 1.
A student studies that a plane mirror results in a laterally inverted image after reflecting. Which of these represents the image likely to be formed by a plane mirror? (Thinking Based Que.)
Question 2.
A student is asked to focus sunlight using two different lenses onto a paper.
Observe the image carefully and answer the following questions. (Experimental Skill)
(i) State the name for the shape of lenses X and Y.
(ii) Which of these two lenses can be used to magnify images?
(iii) Explain the changes that happen to the paper kept under both the lenses.
(iv) Differentiate between convex and concave lenses.
Question 3.
Ayesha keeps a toy in front of a plane mirror, then she looks at the mirror to see the image of the toy. (Competency Based Que., CBSE Diskha)
(i) At which point will the image of the toy be formed in the mirror?
(a) Point 1
(b) Point 2
(c) Point 3
(d) Point 4
(ii) What type of image is formed in the mirror?
(a) Real and upright
(b) Virtual and upright
(c) Real and upside down
(d) Virtual and upside down
Light Mirrors and Lenses Extra Questions for Practice
Very Short Answer Type Questions
Question 1.
Which lens always forms diminished images, irrespective of the position of the object?
Question 2.
Does a concave lens form real or virtual images?
Question 3.
In a torch, light is made to travel in a straight beam. Which mirror helps in this?
Question 4.
Why does a convex mirror allow you to see a larger area behind a vehicle?
Question 5.
You raise your right hand, but your mirror image appears to raise the left. What is this effect called?
Short Answer Type Questions
Question 1.
A student writes ‘SCIENCE’ on paper and holds it in front of a plane mirror. Describe the image formed.
Question 2.
Distinguish between concave and convex mirrors based on (a) Shape (b) Image nature.
Question 3.
How can you show the difference in light behavior through concave and convex lenses using a torch and a screen?
Question 4.
Why do some letters like A, H, and O not appear laterally inverted in a mirror?
Long Answer Type Questions
Question 1.
Explain the differences between concave and convex mirrors and mention two uses of each. Draw ray diagrams to show the nature of image formation.
Question 2.
Describe how a convex lens forms different types of images depending on the position of the object. Support your answer with labelled ray diagrams.
Question 3.
A boy stands in front of a plane mirror with a letter “P” on his shirt, (a) Draw the ray diagram showing reflection from the mirror, (b) How will the letter appear in the mirror? Explain why.