Class x (science chapter - 1)

Light - Reflection and Refraction

(Very short answer type question leh picture hi note a copy thlak hnuah byheart nghal vek tur. Surprise online test neih a ni bawk ang. Explanation chu remchangah upload leh a ni ang. Zawh chian duh nei chuan comment section ah khuan zawh tur, page hnuai berah a awm ang)

B. Very short Answer Type Question

1. Name the mirror that can give an erect and enlarged image of an object.

Answer-

The mirror that can give an erect and enlarged image of an object is Concave Mirror

2. What is the minimum number of rays required for the formation of an image formed by a spherical mirror?

Answer- two

3. Which mirror is used in search light?

Answer- concave mirror is used in search light

4. Define the principal focus of a concave mirror.

Answer-

Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is called the principal focus of the concave mirror.

5. If the image formed by a lens is always diminished and erect, what is the nature of the lens?

Answer - concave lens

6. Name the lens which has (i) virtual focus (ii) real focus

Answer-(i) concave lens (ii) convex lens

7. Define 1 dioptre of power of a lens.

Answer-

Dioptre is the SI unit of power of lens is denoted by the letter D. 1 dioptre can be defined as the power of a lens of focal length 1 metre.

8. Find the power of a concave lens of focal length 2 m.

Answer-

Focal length of concave lens (f) = 2 m

Power of lens (P) = 1/f = 1/ (-2) = -0.5D

9. The magnification produced by a mirror is +1. What does it mean?

Answer- The magnification produced by a plane mirror is +1 means then the size of the image is equal to the size of the object

10. If the magnification of a concave mirror is - 1. What is the position of the object?

Answer - The object must be at the centre of curvature of concave mirror. The image formed is real,inverted and sae size of the object. That is why magnification is -1

11. What is refractive index related to velocity of light?

Answer - The refractive index is equal to the speed of light in a medium divided by the speed of light in a vacuum.

n=vc

12. Name the point inside the lens through which ray of light goes undeviated. 

Answer- The point on the lens through which a ray of light passes undeviated is optical centre.

D. Short Answer Type Question (type - II)

1. Name the type of mirror used in the following situations.

(a) Headlights of a car

(b) Side/rear-view mirror of a vehicle

(c) Solar furnace

Answer-

(a) Concave Mirror: Because concave mirrors can produce powerful parallel beam of light when light source is placed at their principal focus.

(b) Convex Mirror: Because of its largest field of view.

(c) Concave Mirror: Because it concentrates the parallel rays of sun at principal focus