These TS 7th Class Science Important Questions 9th Lesson Reflection of Light will help the students to improve their time and approach.
TS 7th Class Science Important Questions 9th Lesson Reflection of Light
Question 1.
When will you be able to see clear image of yourself in a plane mirror?
Answer:
You will be able to see clear image of yourself in a plane mirror if there is sufficient light in that room.
Question 2.
Will you be able to see your image in a mirror if the mirror is in front of you in a darkroom?
Answer:
I am not able to see the image in a mirror if the mirror is in front of me in a darkroom.
Question 3.
Why should we keep mirror strips parallel to each other in periscope?
What happens if they are not parallel ?
Answer:
In a periscope, the incident ray for the second mirror is the reflected ray of the first mirror. if these mirrors are parallel, then only the rays in the same plane pass through the windows of the periscope. Then only we can see the object through periscope. If the mirrors are not parallel, we cannot see the object through periscope.
Question 4.
What is the angle between two plane mirrors in periscope?
Answer:
The angle between two arranged plane mirrors in the periscope in 45°.
Question 5.
Write the laws of reflection?
Answer:
- The incident ray, the reflected ray and the normal lie in the same plane.
- The angle of incidence is always equal to the angle of reflection i.e. ∠i = ∠r.
Question 6.
To see any object, light should fall on it. In day time we are able to see all objects which are in our room even though sunlight does not fall directly on those objects. How is it possible?
Answer:
In day time, we are able to see all objects which are in our room even though sunlight does not fall directly on those objects. The multiple reflections of sun light from surfaces like wall, floor, ceiling etc, finally fall on the objects and get reflected by them and reach us. This enables us to see the object.
Question 7.
All of you are sitting in your class room, where and how would you place a mirror to see a tree which is outside the class? Can all of you see that tree at a time? If not, what will you do so that each one of you can see the tree without changing your seat?
Answer:
We should place the mirror opposite to the tree which is outside the class. All cannot see that tree at a time. Without changing your seat, one by one can see the tree which is outside the class, by moving the mirror.
Question 8.
Anuvugani chota adhikulamanaradu
Konchamundutella koduva kadu
Konda addamandu konchamai undada
Viswadabhi rama vinuravema
Have you heard this poem?
Why does a mountain look tiny in the mirror?
Answer:
In a mirror, the size of the object looks smaller than its original size. So, a mountain looks tiny in a mirror.
Question 9.
Every day, we see our image in a plane mirror. Is it a real or virtual image? How can you decide?
Answer:
The image that can be obtained on a screen is called a real image. We can see the image in the mirror.
Question 10.
On the front side of ambulances, the word AMBULANCE is written like 
Why?
Answer:
In a mirror, right of an object appears left and left of the object appears right due to lateral inversion. Hence, the front moving vehicles will observe in their rear view mirror and give the way to ambulance.
Question 11.
Observe the image of the sun or a tree in still water. Later, disturb the water by throwing a pebble. How does the image of the sun or the tree appear now ? Why?
Answer:
The image of the sun or a tree in still water seems to be the same. It is a regular reflection and clear image is formed. By throwing a pebble, the surface of the water is disturbed. Now, the surface becomes rough surface. Images are not clear due to irregular reflection.
Question 12.
Fix a candle before two mirrors to attain five images. Find the angle between the two mirrors?
Answer:
To attain five images of a candle the angle between the mirrors must be 600.
Question 13.
What are the required materials you collected and used for making periscope?
Answer:
The following materials are used to make the periscope.
Empty agarbatti box, two mirror strips, scale, pencil, blade, match box, candle, glue.
Question 14.
Collect the information about the objects which are like mirrors in your school and also in your house. Write the common features.
Answer:
The following objects act as mirrors.
- Steel plate, glass
- Cycle bell
- Mirrors of the window
- Black part of the eye
- Surface of the water in a pot or a bucket
Question 15.
Observe the figure and complete the following table.
Answer:
Question 16.
Observe the given diagram. M represents Mirror A, B, C &D represent four students. Whose image is seen by whom? Write the answer.
Answer:
The image of A is seen by C. At the same time, the image of C is seen by A.
The image of B is seen by D and the image of D is seen by B.
Question 17.
Where do you find irregular reflection in your daily life? Give examples.
Answer:
Reflection from a rough or irregular surface is called irregular reflection or diffused reflection.
Examples :
- Reflection on the pieces of ice.
- Reflection on the disturbed water surface.
- Reflection on the surface of the window glass which is rough.
Choose the correct answer:
I. Conceptual Understanding
Question 1.
The image formed on the screen is called ( )
A) real image
B) virtual image
C) A and B
D) none of these
Answer:
A) real image
Question 2.
The relation between incident angle ∠i and reflected angle ∠r is( )
A) ∠i >∠r
B) ∠i < ∠r
C) ∠i = ∠r
D) ∠i+∠r = 0
Answer:
C) ∠i = ∠r
Question 3.
Reflection from a smooth surface is called ( )
A) irregular reflection
B) regular reflection
C) A and B
D) none of these
Answer:
B) regular reflection
Question 4.
Reflection from a rough surface is called ( )
A) regular reflection
B) irregular reflection
C) A and B
D) none of these
Answer:
B) irregular reflection
Question 5.
In a periscope, the two mirrors are kept
A) perpendicular
B) slope
C) parallel
D) any way
Answer:
C) parallel
Question 6.
In a mirror are reversed
A) right, left
B) top, bottom
C) A and B
D) none
Answer:
A) right, left
Question 7.
The image that can’t be obtained on a screen is called …………
A) real image
B) virtual image
C) erect image
D) none
Answer:
B) virtual image
Question 8.
The angle of incidence and angle of reflection are ( )
A) not same
B) unequal
C) equal
D) no change
Answer:
C) equal
Question 9.
In the image formed by a mirror, right and left are reversed.This is called ( )
A) lateral inversion
B) vertical inversion
C) front inversion
D) longitudinal inversion
Answer:
A) lateral inversion
Question 10.
The angle between two mirrors in 900. Then the number of images is ( )
A) 2
B) 3
C) 4
D) 6
Answer:
B) 3
Question 11.
If the angle between the plane mirror is 600, then the number of images formed are ( )
A) 1
B) 5
C) 4
D) 3
Answer:
B) 5
II. Asking Questions and Making Hypothesis
Question 12.
If concave mirror is not arranged in the head light of motor bike, what would be the result? ( )
A) Reflection and focus of light increases
B) Reflection and focus of light decreases
C) Reflection and focus are destroyed
D) Reflection and focal length expand.
Answer:
B) Reflection and focus of light decreases
Question 13.
Concave mirror: used by dentist :: convex mirror ? ( )
A) used in microscope
B) used in cars
C) used in planes
D) used in torch
Answer:
B) used in cars
III. Experimentation and Field investigation
Question 14.
How many number of mirrors were used by you in making periscope.
A) 1
B) 3
C) 2
D) 5
Answer:
C) 2
Question 15.
The number of mirror strips used in making of kaleidoscope. ( )
A) 2
B) 3
C) 4
D) 1
Answer:
B) 3
IV. Information Skills and Projects
Question 16.
This is the place where more mirrors are used. ( )
A) House
B) Temple
C) Hill
D) Flair saloon shop
Answer:
D) Flair saloon shop
Question 17.
Rough surface of mirror gives reflection. ( )
A) irregular
B) regular
C) equal
D) unchanges
Answer:
A) irregular
V. Communication through Drawing and Model Making
Question 18.
The given picture shows ( )
A) regular reflection on the mirror
B) irregular reflection on the mirror
C) equal reflection on the mirror
D) more equal reflection on the mirror
Answer:
B) irregular reflection on the mirror
Question 19.
The given picture of mirror is … ( )
A) convex mirror
B) plane mirror
C) rough mirror
D) concave mirror
Answer:
D) concave mirror
Question 20.
In the given picture, the image of the candle is small in the mirror. What type of mirror is used? ( )
A) concave mirror
B) convex mirror
C) contract mirror
D) above all
Answer:
B) convex mirror
VI. Appreciation and Aesthetic Sense and Values
Question 21.
Mirror used by Dentist.
A) Concave mirror
B) Convex mirror
C) Plane mirror
D) None of these
Answer:
A) Concave mirror
Question 22.
The surface behind the torch light and bulb in head light of a vehicle.
A) Convex
B) Concave
C) Plane
D) None of these
Answer:
B) Concave
Question 23.
Mirror used as a rear view mirror. ( )
A) Convex
B) Spherical
C) Plane
D) Concave
Answer:
A) Convex