Kerala SSLC Notes Class 10 Science Reflection of Light
Kerala SSLC Notes Class 10 Science Part 1 Book for Chapter 4 Reflection of Light by SSLC Teacher Kerala Class 10 Board Exam. This SSLC Notes Class 10 Science will help students to prepare for Kerala Syllabus sslc Science .
Kerala Education department directly manages 14000+ schools, 160K+ teachers ,20K+ non teaching staff of the state.[Details in Sametham -the complete School Databank, SchoolWiki – Wiki of each Individual schools].The Department plays an eminent role in the physical and mental development of all pupils studying in schools. There has been tremendous growth in educational facilities at all levels of education in the state during the last 50 years. Here we have given Kerala SSLC Notes Class 10 Science Chapter 4 World in the Twentieth for English Medium Kerala Syllabus.
SSLC Notes Class 10 Science – Reflection of Light
Multiple Choice Questions:
1.) According to laws of reflection, the angle of incidence and angle of _____ are equal.
a) reflection
b) refraction
c) both a and b
d) none
Ans: a) reflection
2.) In regular reflection, the rays after reflection becomes ______.
a) perpendicular to each other
b) intersect each other
c) parallel to each other
d) cannot predict
Ans: c) parallel to each other
3.) The image formed in plane mirror is ______
a) virtual
b) erect
c) both a and b
d) real and erect
Ans: c) both a and b
4.) The formula for number of images found is
a) 180/angle – 1
b) 360/angle – 1
c) 360/angle – 2
d) 180/angle -2
Ans: b) 360/angle – 1
5.) If the angle between two mirrors is 90° then the number of images formed are
a) 4
b) 2
c) 5
d) 3
Ans: d) 3
6.) What is the mirror equation or mirror formula
a) 1/f = 1/u – 1/v
b) 1/f = 1/u + 1/v
c) f = uv/u+v
d) both b and c
Ans: d) both b and c
7.) Which of the following shows magnification formula
a) v/u
b) u/v
c) -v/u
d) -u/v
Ans: c) -v/u
8.) When the object is placed between the focus and centre of curvature in case of concave mirror the image formed is
a) same as the actual object
b) point sized
c) smaller than actual object
d) larger than the actual object
Ans: d) larger than the actual object
9.) The rear-view mirrors fitted in vehicles are
a) concave mirrors
b) plane mirrors
c) convex mirrors
d) both a and b
Ans: c) convex mirrors
10.) The magnification produced by rear view mirrors is found to be
a) more than 1
b) equal to 1
c) less than 1
d) can’t predict
Ans: c) less than 1
11.) If we have to see the whole image of the distant taller tree which mirror we can use
a) concave mirror
b) convex mirror
c) plane mirror
d) both a and c
Ans: b) convex mirror
12.) The images produced by convex mirrors are
a) diminished
b) virtual
c) erect
d) all above
Ans: d) all above
13.) In torches, search lights and head lights of vehicles which mirrors are used
a) plane mirror
b) concave mirror
c) convex mirror
d) both a and b
Ans: b) concave mirrors
14.) The image produced is highly diminished and point size when object is at infinity means which mirror is used
a) concave mirror
b) convex mirror
c) plane mirror
d) both a and b
Ans: d) both a and b
15.) When the size of image and object are equal
a) m<1
b) m>1
c) m=1
d) cannot say
Ans: c) m= 1
Very Short Answer Questions:
1.) When the image formed by the concave mirror is larger than the actual object?
Ans: The image formed by the concave mirror is larger than actual object only when we place the object in between focus of the concave mirror and the centre of curvature of the concave mirror.
2.) In case of concave and convex mirrors when the image formed will be highly diminished and point sized?
Ans: In case of concave and convex mirror the image produced will be highly diminished and point sized only when the object is placed at infinity.
3.) What is the second law of reflection?
Ans: The second law of reflection states that, the angle of reflection and angle of incidence always become equal.
4.) Define concave mirror.
Ans: Concave mirror is the type of spherical mirror in which outer surface is polished surface and inner bent surface or concave surface is the surface from which light get reflected.
5.) Define principal focus or focal point of spherical mirror.
Ans: The common point on the principal axis is called as principal focus or focal point of the spherical mirror.
5.) What is the focal length of spherical mirror?
Ans: The distance between principal focus or focal point of the spherical mirror and pole of the spherical mirror is called as focal length of the spherical mirror.
It is denoted by f.
5.) What is the focal length of spherical mirror?
Ans: The distance between principal focus or focal point of the spherical mirror and pole of the spherical mirror is called as focal length of the spherical mirror.
It is denoted by f.
7.) What is the relationship between radius of curvature and focal length of the spherical mirror?
Ans:
Following is the relationship between focal length f and radius of curvature R of the spherical mirror.
R = 2f
8.) When the object is placed at infinity in case of concave mirror then the image formed will be where?
Ans:
When the object is placed at infinity in case of concave mirror, the image formed will be at the focus of concave mirror.
9.) In case of concave mirror when the image formed is virtual and erect?
Ans:
In case of concave mirror, the image formed is virtual and erect only when the object is placed in between pole P and focus F of the concave mirror.
10.) Concave mirror is also called as?
Ans:
Concave mirror is also called as converging mirrors due the converging property.
11.) Which type of mirrors used by dentist to see the small parts in enlarged size?
Ans:
Concave mirrors are used by dentist to see the small parts in enlarged size.
12.) In case of convex mirror if the object is kept between infinity and pole P of the mirror then where will be the image formed?
Ans:
In case of convex mirror, when the object is placed in between infinity and pole P of the mirror the image will be formed between pole P and focus F behind the mirror.
13.) What is real image?
Ans:
An image which we can take or capture on a screen is called as real image.
14.) What is virtual image?
Ans:
An image which cannot be taken on screen is called as virtual image.
15.) Mention the relationship between image distance and object distance.
Ans:
The relationship between image distance v and object distance u is as follows.
1/v + 1/u = 1/f
Short Answer Questions:
1.) What is the magnification formula and give about its sign conventions.
Ans:
The magnification formula is as given below.
Magnification m = -v/u
Where,
V is the image distance
U is the object distance
In case of magnification m, if m is negative that means the image formed is real.
And if m is positive then image formed is virtual.
2.) State the three laws of reflection.
Ans:
Following are the three laws of reflection.
- First law: The incident ray, normal at the point of incidence and the reflected ray all lie in the same plane.
- Second law: The angle of incidence and angle of reflection always become equal.
- Third law: The incident ray and the reflected ray both lie on the opposite sides of the normal.
3.) Give any three uses of concave mirrors.
Ans:
Following are the uses of concave mirrors:
- Concave mirrors are used to large image of the ace in mirror in Parlors and shaving shops.
- As concave mirror possesses converging property that’s why they are used to store huge amount energy from sunlight.
- To see large image of the object concave mirrors are also used by dentist.
- To see objects which are distant apart in dark concave mirrors are used in torches, search lights and headlights of the vehicle.
4.) Mention any two uses of convex mirrors.
Ans:
Following are the uses of convex mirrors:
- Convex mirrors are most of the time used in vehicles to see the vehicles which are distant apart from them.
- Only because of convex mirror the driver can see the full image of vehicle behind him in order to keep safe driving.
5.) Give any four sign conventions in case of reflection by spherical mirror.
Ans:
Following are the sign conventions in case of reflection by spherical mirror:
- The distances measured above and normal to the principal axis are taken as positive.
- Distances measured below and normal to the principal axis are taken as negative.
- All the distances are measured from the pole P of the spherical mirror.
- If the image of the object formed is real then image distance v is taken as negative.
- If the image of the object formed is virtual then image distance v is taken as positive.
- Focal length of concave mirror is negative and focal length of convex mirror is positive.
6.) In case of concave mirror, the object distance is 7cm and radius of curvature is 40cm. Then what will be the image distance and nature of the image also.
Ans:
For concave mirror:
Object distance u = -7cm
Focal length f= R/2 = 40/2 = -20cm
Now,
1/f = 1/v + 1/u
1/-v + 1/(-7) = 1/(-20)
Since, image distance v also negative.
Thus, v = – 0.1cm
Hence, the image formed is virtual, erect and magnified here.
7.) In case of convex mirror, the object distance is 5cm and focal length is 15cm then what is the image distance?
Ans:
For convex mirror:
Object distance u= -5cm
Focal length f = 15cm
Then,
1/v + 1/u = 1/f
1/v + 1/(-5) = 1/15
1/v = 20/75
V = 3.75cm
Thus, the image distance is found to be 3.75cm
8.) Explain about the image formed in case of plane mirrors.
Ans:
Following are the characteristics of images formed in plane mirrors:
- The image formed is virtual.
- The image formed is laterally inverted also.
- The image formed is of the same size as the object size.
- The distance of the image from the mirror is same as the distance of the object from the mirror.
9.) Explain the conditions of magnification and sign conventions.
Ans:
The magnification formula is given as
Magnification m = -v/u
- If the magnification m=1, that means the size of the image and object is equal.
- If magnification m >1, that means the image size is greater or larger than object size.
- If magnification is m<1, that means image size is smaller than the object size.
- If m is positive that means the image formed is real and inverted.
- If m is negative that means the image formed is virtual and erect.
10.) Explain reflection of light with neat labelled diagram.
Ans:
- When a ray of light striking the plane surface bounce back in the same medium it is called as reflection of light. And during reflection of light all the laws of reflection are followed.
- The following figure shows the reflection of light from plane surface.
- PO is the incident ray, OQ is the reflected ray, MN is the normal to the plane surface, I is the angle of incidence and r is the angle of reflection.
And follows the laws of reflection which are stated as follows.
1) When the ray of light is reflected from plane surface, the angle of incidence (i) and the angle reflection r both are equal.
2) The incident ray, the normal and the reflected ray all lie in the same plane.
11.) Differentiate between regular reflection and irregular reflection of light.
Ans:
There are two types of reflection namely regular reflection and irregular reflection.
Following figure, a) shows regular reflection.
Regular reflection:
- Regular reflection is the reflection of light in which light is reflected from the plane surface like plane mirror, polished surface and after reflection all the reflected rays goes parallel as shown in figure a).
Irregular or diffused reflection:
- Irregular or diffused reflection is that type of reflection in which reflection of light takes place from rough surface and after reflection the rays of light not reflected parallel as shown in figure b).
- In case of scattering of light there is reflection of light occurs from the dust particles present in the atmosphere. Plane mirrors and spherical mirrors are the mirrors in which regular reflection of light takes place.
12.) Differentiate between plane mirror, concave mirror, and convex mirrors.
Ans:
There are three types of mirrors plane mirrors, concave mirrors, and convex mirrors. The image produced by each mirror is different in nature, size, and position.
Plane Mirrors:
- In case of plane mirrors image of the object is formed behind the mirror.
- Distance of object from the mirror (object distance) and the distance of image from the mirror (image distance) are equal.
- The image formed is virtual, erect and having same size as the object size.
- Plane mirrors are mostly used for observing the face.
Concave mirrors:
- In case of concave mirrors, the rays parallel to principal axis are converged at the principal focus F.
- The rays emerging when object is placed at principal focus are parallel to the principal axis.
- When the object is placed in between principal focus F and pole P of the concave mirror the images formed are enlarged and erect.
Convex mirror:
- Image is formed in between principal focus F and pole P.
- The image formed is diminished, virtual and erect.
- Convex mirrors are mostly used as rear-view mirrors.
- The maximum range of the vision through the mirror is called as the field of view of the mirror.
- As the images formed by different mirrors are different hence the filed of view of each mirror is also different.
- The field of view is maximum for convex mirror and hence they are used as rear view mirrors.
13.) Explain magnification in detail.
Ans:
Magnification is the ratio of height of image to the height of object & it is denoted by m.
m = height of the image/ height of the object =h’ /h
Magnification in terms of image distance & object distance is given as
Magnification m = h’/h = -v/u
Magnification gives the relative extent of magnified image with respect to the original object size.
- If the magnification m=1, that means the size of the image and object is equal.
- If magnification m >1, that means the image size is greater or larger than object size.
- If magnification is m<1, that means image size is smaller than the object size.
- If m is positive that means the image formed is real and inverted.
- If m is negative that means the image formed is virtual and erect.
14.) What will be the nature of the image in case of concave mirrors when the object is placed at positions given below.
a) at infinity
b) beyond C
c) at C
Ans:
For concave mirrors:
a) If the object is placed at infinity, then image will be formed at focus which is highly diminished, point sized, real and inverted.
b) If the object is placed beyond C in case of concave mirror, then image will be formed between F and C which will be diminished, real and inverted.
c) If the object is placed at C in case of concave mirror, then image will be formed at C which will be of same size as object size, real and inverted.
15.) What will be the nature of the image in case of convex mirrors when the object is placed at the positions given below.
a) at infinity
b) between infinity and pole P of the mirror
Ans:
For convex mirrors:
a) If the object is placed at infinity in case of convex mirror, then the image will be formed at the focus F behind the mirror which will be highly diminished and point sized.
b) If the object is placed between infinity and pole P of the convex mirror then image will be formed between P and F behind mirror which will be diminished, virtual and erect.
Long Answer questions:
1.) Explain the process of multiple reflection and Image formation with the help of suitable diagram.
Ans:
• To discuss multiple reflection and image formats we will do one activity. Take two plane mirrors and place them perpendicular to each other as shown in figure and keep the burning candle as an object exactly at the position given in figure. Now observe the images of the burning candle from the two positions A and B as shown. How many images you can observe? The answer is images formed are three in number because here two plane mirrors are perpendicular to each other. And the angle between these two mirrors is 90°. Now change the angle between these two mirrors and observe the number of images formed here.
- By taking different angles finally we can find the generalized formula for number of images formed as below.
Number of images (n) = (360/Angle between two plane mirrors) – 1
For example:
1.) When angle is 90°.
N = 360/90-1 = 4-1= 3
Means, 3 images are formed when two mirrors are perpendicular to each other.
2.) When the angle between two mirrors is 120°.
The number of images formed are
N = 360/120 – 1 = 3-1= 2
Hence, when angle between two mirrors is 120° two images are formed.
2.) Explain the process of image formation in case of plane mirrors with the help of neat labelled diagram.
Ans:
- In case of reflection of light in plane mirrors decide the position of image, nature of image and all.
- We are seeing how images are formed by the plane mirrors. Let us consider the point O as a light source which is placed in front of the plane mirror. OA and OC are the rays of light which are incident obliquely as shown in figure below. These rays follow the laws of reflection and reflected as AB and CD with respect to the normal MN and M’N’ respectively. When we will extend these reflected rays AB and CD in backward direction, it is found that they meet at point I as shown. And this point I is nothing but the image formed here.
- In this way images are formed in case of plane mirrors. And the image formed is virtual image of same size as the object. Also, in case of plane mirrors the object distance is equal to the image distance.
- If we are increasing the number of plane mirrors here then the light rays reflected again acts as a incident rays and undergoes multiple reflection and produces multiple images.
3.) Draw the ray diagrams in case of concave mirrors when object is placed at following positions.
a) At C
b) Between C and F
c) At F
Ans:
Following are the ray diagrams which shows image formation in case of concave mirrors when object is placed at given positions.
a) At C