THESE NOTES ARE PREPARED ACCORDING TO JKBOSE SYLLABI IN SIMPLIFIED AND CONCISE PATTERN
Exercises
1. Fill in the blanks:
a. An image that cannot be obtained on a screen is called Virtual image .
b. Image formed by a convex Mirror is always virtual and smaller in size.
c. An image formed by a Plane mirror is always of the same size as that of theobject.
d. An image which can be obtained on a screen is called a Real image.
e. An image formed by a concave Lens cannot be obtained on a screen.
2. Mark 'T' if the statement is true and 'F' if it is false:
a. We can obtain an enlarged and erect image by a convex mirror.(T/F)
False
b. A concave lens always form a virtual image.(T/F)
True
c. We can obtain a real, enlarged and inverted image by a concave mirror. (T/F)
True
d. A real image cannot be obtained on a screen.(T/F)
False
e. A concave mirror always forms a real image.(T/F)
True 5 out of 6 times
3. Match the items given in Column I with one or more items of Column II
Ans:
a. A plane mirror : v. The image is erect and of same size as the object.
b. A convex mirror : ii. Can form image of objects spread over a large area.
c. A convex lens : i. Used as a magnifying glass
d. A concave mirror: iii. Used by dentists to see enlarged image of teeth
e. A concave lens: vi. The image is erect and smaller in size than the object
4. State the characteristics of the image formed by a plane mirror?
Ans: The characteristics of image formed by a plane mirror are:
1. The image is erect
2. The image is of same size as the object.
3. The image is at the same distance from mirror as the object.
4. The image is virtual.
5. The image is laterally inverted.
5. Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings?
Ans: The letters of english alphabets in which image formed in a plane mirror appear exactly like the letter itself are:
W, T, Y, U, I, O, A, H, X, V, M
6. What is a virtual image? Give one situation where a virtual image is formed?
Ans: The image that cannot be obtained on a screen is called Virtual image.
In virtual image, the rays of light do not actually meet.
Situation: When we see our image in a plane mirror, it is a virtual image.
7. State two differences between a convex and a concave lens?
Ans:
The convex lens converges rays of light where as concave lens diverges rays of light.
The convex lens in thick at centre where as concave lens is thin in centre.
The convex lens forms real image whereas concave lens forms virtual image.
8. Give one use each of a concave and a convex mirror?
Ans:
Uses of Concave mirror:
It is used by dentists,
It is used as reflector of torches.
Uses of Convex mirror:
It is used as side view mirror in cars,
It is used at blind curve on roads.
9. Which type of mirror can form a real image?
Ans: The concave mirror can form a real image.
10. Which type of lens always forms a virtual image?
Ans: The concave lens always forms a virtual image.
Choose the correct option in question11-13
11. A virtual image larger than the object can be produced by a
(i) Concave lens (ii) Concave mirror
(iii) Convex mirror (iv) Plane mirror
Ans: ii. Concave mirror.
Explanation: The concave mirror forms real image 5 out of 6 times. But if the object is between focus and pole of mirror, it forms virtual image which is larger than the object.
A
12. David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be
(i) 3m (ii) 6m (iii) 5m (iv) 8m
Ans: (ii) 6 m
13. The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2m/s. The driver sees in his rear view mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be
(i) 1m/s (ii) 2m/s (iii) 4m/s (iv) 8m/s
Ans: (iii) 4 m/s
Explanation: When car moves towards truck at the speed of X, then in the mirror the truck will seem to move towards the car at the speed of 2X.
(i) 3m (ii) 6m (iii) 5m (iv) 8m
Ans: (ii) 6 m
13. The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2m/s. The driver sees in his rear view mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be
(i) 1m/s (ii) 2m/s (iii) 4m/s (iv) 8m/s
Ans: (iii) 4 m/s
Explanation: When car moves towards truck at the speed of X, then in the mirror the truck will seem to move towards the car at the speed of 2X.
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