NCERT Science Class 10 Chapter 10 Light-Reflection and Refraction CBSE Board Sample Problems Very Short Answer
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Question
Define one dioptre of power of a lens?
Solution
Power of a lens is one dioptre if focal length of a lens is 1 m.
Question
Name the kind of surfaces that
(i) Reflect
(ii) Refract most of the light falling on them.
Solution
(i) Optically Plane surface
(ii) Transparent surface
Question
Name the mirror that can give an erect and enlarged image of an object?
Solution
Concave mirror
Question
What is the angle of incidence and angle of reflection when light is falling normally on concave mirror?
Solution
Both the angles will be 0
Question
Name any two factors on which lateral displacement in case of a glass slab depends.
Solution
Angle on incidence
Thickness of the glass slab
Question
The magnification produced by a mirror is -1. What is your conclusion by the nature of mirror used and the position of the object?
Solution
Concave mirror and the object is at C
Question
What is the minimum distance between the object and its real image in case of a concave mirror?
Solution
Zero
Question
In which direction, a ray of light bends when it goes from water to glass?
Solution
It will bend towards the normal.
Question
An object is placed 80 cm from converging lens of focal length 25 cm. What is the nature of image?
Solution
The image is real, inverted and diminished as the object is placed beyond 2F.
Question
Under what conditions a lens becomes invisible when placed in a transparent liquid?
Solution
This happens when refractive index of the lens becomes equal to that of liquid
Question
Refractive index of two material mediums X and Y are 1 .3 and 1.5 respectively. In which of the two, the light would travel faster?
Solution
In medium X because of lower value of refractive index.
Question
Between which two points of a concave mirror should an object be placed to obtain a virtual magnified image?
Solution
Between F and P.
Question
A man standing in front of a spherical mirror, finds his image having a very small head, a fat body and legs of normal size. What types of mirrors are used in this part?
Solution
A very small head: convex mirror
A fat body: concave mirror, and
Legs of normal size: plane mirror
Question
The following questions consists of two statements - Assertion (A) and Reason (R).
Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is correct explanation of A.
(b) Both A and R are true and R is not correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true
Assertion (A): Refractive index have no units.
Reason (R): the refractive index is ratio of two similar quantities.
Solution
(a)
Question
The following questions consists of two statements — Assertion (A) and Reason (R).
Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is correct explanation of A.
(b) Both A and R are true and R is not correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true
Assertion (A): A convex mirror is used as a rear view/driver’s mirror.
Reason (R): convex mirror have a wider field of view as they are curved outwards.
They also give an erect, though diminished image.
Solution
(a)
Question
An object 5cm high is placed at a distance 2f from a convex lens. What is the height of the image formed? (1)
Solution
The height of image=height of the object= 5cm. (1)