Light: Mirrors and Lenses Class 8 Extra Questions and Answers Science Chapter 10

Students can keep Class 8 Science Extra Questions and Class 8th Curiosity Chapter 10 Light: Mirrors and Lenses Important Extra Question Answer handy for quick reference during exams.

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.
What makes things visible?
Answer:
When light from an object reflects and enters our eyes, then we see that object.

Question 2.
Do we see all objects due to reflected light?
Answer:
Almost everything we see around us can be seen due to reflected light. Moon, for example, receives light from the sun and reflects it. That’s why we see the moon.

Question 3.
What happens when light falls on a mirror?
Answer:
The mirror is silvered on one side, so it does not allow the light to pass through it. It reflects almost the whole of the light that falls on it.

Question 4.
What change in the path of light takes place when light falls on a shiny surface? What is this called?
Answer:
The light reflects in the same plane when light falls on a shiny surface. This is known as the reflection of light.

Question 5.
What is a reflected ray?
Answer:
The ray that gets reflected from the surface of a shiny object is known as the reflected ray.

Question 6.
What is an incident ray?
Answer:
The ray of light that strikes any surface is called the incident ray.

Question 7.
How many reflected rays can there be for a given single incident ray falling on a plane mirror?
Answer:
For one incident ray, there is one and only one reflected ray.

Question 8.
How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other? (NCERT Exemplar)
Answer:
An infinite number of times.

Question 9.
The angle between the incident ray and the reflected ray is 60°. What is the value of the angle of incidence? (NCERT Exemplar)
Answer:
30°

Question 10.
The distance between the object and its image formed by a plane mirror appears to be 24 cm. What is the distance between the mirror and the object? (NCERT Exemplar)
Answer:
12 cm

Light: Mirrors and Lenses Class 8 Short Question Answer

Question 1.
Describe the nature of the image formed by:

• A plane mirror.
• A convex mirror.
• A concave mirror.

Answer:

• Plane Mirror: Forms a virtual, upright, same-sized image behind the mirror.
• Convex Mirror: Forms a virtual, upright, diminished image behind the mirror.
• Concave Mirror: Forms a real or virtual image depending on the object’s position.
  Generally, the image is inverted and magnified if real; upright and magnified if virtual.

Question 2.
Can a real image be obtained on a screen? Explain briefly.
Answer:
Yes, a real image can be obtained on a screen. Real images are formed by the actual convergence of light rays, allowing them to be projected onto a surface.

Question 3.
Why is a convex mirror called a diverging mirror?
Answer:
A convex mirror is called a diverging mirror because it reflects light rays outward, making them spread apart and appear to come from a point behind the mirror.

Question 4.
State two uses of a concave mirror.
Answer:
Reflecting telescopes gather and focus light from distant objects.
Shaving or makeup mirrors because they magnify the face when held close.

Question 5.
State two uses of a convex lens.
Answer:
Magnifying glasses, to enlarge small objects for better visibility.
Cameras and microscopes focus light and form clear, sharp images.

Question 6.
What are the characteristics of the image formed by a plane mirror?
Answer:
Characteristics of images formed by a plane mirror are:

• The mirror forms an erect image.
• The image formed is of the same size as the object.
• The distance of the image from the mirror is equal to the distance of the object from the mirror.
• It is virtual; it can’t be obtained on a screen.

Question 7.
What are the angles of incidence and reflection?
Answer:

• Angle of Incidence: The angle between the normal and the incident ray is called the angle of incidence.
• Angle of Reflection: The angle between the normal and the reflected ray is called the angle of reflection.

Light: Mirrors and Lenses Class 8 Long Question Answer

Question 1.
Explain why a convex mirror always forms a virtual and diminished image, irrespective of the object’s position.
Answer:
A convex mirror is a diverging mirror, meaning it spreads out parallel light rays after reflection.
Its focus (F) and center of curvature (C) are behind the mirror, hence virtual.

When light rays from an object strike a convex mirror, they diverge. These diverging rays, when extended backward, appear to meet at a point behind the mirror, forming a virtual image. Due to this divergence and the geometry, the virtual image is always formed between the pole and the principal focus, and it is always erect and diminished compared to the object.

Question 2.
Differentiate between a concave mirror and a convex mirror based on shape, nature of the image formed, and their two uses.
Answer:

Feature	Concave Mirror	Convex Mirror
Shape	Curved inward, like the inside of a spoon.	Curved outward, like the back of a spoon.
Nature of Image	It can form both real and virtual, inverted and erect, and magnified, diminished, or same-sized images, depending on object position.	Always forms virtual, erect, and diminished images.
Two Uses	Shaving mirrors/Dentists’ mirrors. Headlights of cars/Searchlights.	Rear-view mirrors in vehicles. Security mirrors in shops.

Question 3.
Differentiate between a concave lens and a convex lens based on their shape, the nature of the image formed, and their two primary uses.
Answer:

Feature	Concave Lens	Convex Lens
Shape	Thinner in the middle and thicker at the edges. (Diverging lens)	Thicker in the middle and thinner at the edges. (Converging lens)
Nature of Image	Always forms virtual, erect, and diminished images.	It can form both real and virtual, inverted and erect, and magnified, diminished, or unchanged-sized images, depending on the object’s position.
Two Uses	Correcting short-sightedness (Myopia) Peepholes in doors	Magnifying glass Used in cameras, microscopes, and telescopes

Light: Mirrors and Lenses Extra Questions for Practice

Question 1.
Which lens converges the light rays?

Question 2.
Which lens diverges the light ray?

Question 3.
Which lens is used in a magnifying glass?

Question 4.
Lenses are made up of which material?

Question 5.
Lenses are also used in electronic devices.

Question 6.
Lens that makes parallel rays of light meet at a point are called.

Question 7.
On what principle does a lens work?

Question 8.
Give the name of an optical instrument that uses a lens.

Question 9.
In your classroom room which instrument uses a lens?

Question 10.
Type of image formed by a Concave lens.

Question 11.
What is a lens?

Question 12.
Name the two main types of lenses?

Question 13.
What is a Convex lens?

Question 14.
What is a Concave lens?

Question 15.
What kind of image does a Concave lens always form?

Question 16.
Write down to everyday uses of a Convex lens.

Question 17.
Can a lens form both virtual and real images?

Question 18.
What is a Real Image?

Question 19.
What is a Virtual Image?

Question 20.
Why does a Concave lens never form a real image?

Question 21.
Explain the difference between Convex and Concave lenses.

Question 22.
How do lenses refract light?

Question 23.
Describe how Concave lenses diverge light. What kind of image do they produce?

Question 24.
Compare properties of lenses based on shape, behaviour, type of image formed, and uses.

Question 25.
Define the principal axis, the optical centre, and the focal point of the lens.

MCQs

Question 1.
A lens that is thicker at the center than at the edge is:
(a) Concave lens
(b) Convex lens
(c) Diverging lens
(d) Flat lens

Question 2.
A concave lens is also known as:
(a) Converging
(b) Positive
(c) Diverging
(d) Real lens

Question 3.
The focus of a convex lens is a point where:
(a) Diverging rays appear to come from
(b) Parallel rays diverge after passing through the lens
(c) Parallel rays converge after passing through the lens
(d) Rays reflect back

Question 4.
Which lens can form a real image?
(a) Concave lens only
(b) Convex lens only
(c) Both (a) and (b)
(c) None of the above

Question 5.
Which mirror is used in the Washroom or the dressing Table?
(a) Convex Mirror
(b) Concave Mirror
(c) Plane Mirror
(d) Transparent

Question 6.
The Angle between the incident ray and the normal is called
(a) Angle of reflection
(b) Angle of incidence
(c) Angle of deviation
(d) Focal angle

Question 7.
If for any plane mirror the angle of incidence is 45°, what will be the angle of reflection?
(a) 30°
(b) 45°
(c) 60°
(d) 90°

Question 8.
The direction of the angle of incidence is
(a) Towards the mirror
(b) Away from the mirror
(c) Parallel to the surface of the mirror
(d) None of the above

Question 9.
A Concave mirror is ground in
(a) Outward
(b) Inward
(c) Flat
(d) Zig-Zag

Question 10.
The laws of reflection state that:
(a) Angle of incidence ≠ Angle of reflection
(b) Angle of incident > Angle of reflection
(c) Angle of incident < Angle of reflection
(d) Angle of incident = Angle of reflection

Question 11.
A mirror is made by polishing glass from:
(a) One Surface
(b) Two Surfaces
(c) No Surface
(d) Multiple Surface

Fill in the blanks

Question 1.
A lens is a piece of transparent material bounded by _____________ surfaces.

Question 2.
A Convex lens is _____________ in the middle and thinner at the edges.

Question 3.
A Concave lens is _____________ in the middle and thicker at the edges.

Question 4.
A Convex lens is called _____________ lens.

Question 5.
A Concave lens is called _____________ lens.

Question 6.
The point where light rays meet after passing through a lens is called the _____________

Question 7.
The line passing through the optical center of the lens is called _____________ axis.

Question 8.
The real image is formed when rays _____________ meet a point.

Question 9.
Concave lenses form images that are always _____________ and upright.

Question 10.
Virtual image can only be seen by the _____________

True or False

Question 1.
A convex lens is thicker at the edge than at the center.

Question 2.
A concave lens is also called a diverging lens.

Question 3.
The focal point of a lens is the point where light rays meet or appear to meet.

Question 4.
A magnifying glass uses a concave lens.

Question 5.
A convex lens can form an inverted image.

Question 6.
The principal axis is a straight line passing through the focal point and optical center.

Question 7.
A concave lens is used in a camera to focus light.

Question 8.
A convex lens can form a virtual image when the object is placed between the lens and its focal point.

Question 9.
Concave lenses are used in flashlights to focus light.

Question 10.
The curvature of a lens affects its focal length.

Match the following

Question 1.

Column I	Column II
(a) Convex lens	(i) Diverges light ray
(b) Concave lens	(ii) Used in a magnifying glass
(c) Convex mirror	(iii) Forms a real and inverted image
(d) Concave mirror	(iv) Used in the rear view mirror
(e) Real image	(v) Can be projected on screen