Course Content
Class 7th Science
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Class 7th Math
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Class 7 Social Science Geography
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Class 7 Social Science History
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Class 7 Social Science Civics
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Class 7 English Honeycomb
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Class 7 English Honeycomb Poem
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Class 7 English An Alien Hand Supplementary
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Online Class For 7th Standard Students (CBSE)

Question 1.
Fill in the blanks:

1. An image that cannot be obtained on a screen is called ……….
2. The image formed by a convex ……… is always virtual and smaller in size.
3. An image formed by a ……… mirror is always of the same size as that of the object.
4. An image which can be obtained on a screen is called a ……… image.
5. An image formed by a concave ……… cannot be obtained on a screen.

Solution:

1. virtual image
2. mirror
3. plane
4. real
5. lens.

Question 2.
Mark ‘T’ if the statement is true and ‘F’ if it is false:

1. We can obtain an enlarged and erect image by a convex mirror. (T/F)
2. A concave lens always forms a virtual image. (T/F)
3. We can obtain a real, enlarged, and inverted image by a concave mirror. (T/F)
4. A real image cannot be obtained on a screen. (T/F)
5. A concave mirror always forms a real image. (T/F)

Solution:

1. F
2. T
3. T
4. F
5. F

Question 3.
Match the items given in Column I with one more item of Column II.
Column I
(a) A plane mirror
(b) A convex mirror
(c) A convex lens
(d) A concave mirror
(e) A concave lens

Column II
(i) Used as a magnifying glass.
(ii) Can form images of objects spread over a large area.
(iii) Used by dentists to see enlarged images of teeth.
(iv) The image is always inverted and magnified.
(v) The image is erect and of the same size as the object.
(vi) The image is erect and smaller in size than the object.
Solution:
(a) – (v)
(b) – (ii)
(c) – (i)
(d) – (iii)
(e) – (vi)

Question 4.
State the characteristics of the image formed by a plane mirror.
Solution:

1. The reflected image retains the colour of the object.
2. The image is erect but laterally inverted.
3. Lateral inversion: Right side of the object appears as a left side in the image formed by a plane mirror. For example, if we show our right hand, the image in the mirror will show its left hand.
4. It forms a virtual image.
5. Image is formed at the same distance behind the mirror as the objects in front of the mirror.

Question 5.
Find out the letters of the 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.
Solution:
If the letters of the English alphabet A, H, I, M, O, T, U, V, W, X, Y are kept in front of a plane mirror, then they would form images which exactly look like the original letters of the alphabet. These letters are vertically symmetric. For example, if we divided letters A and U in the middle, then we would find that the right halves are equivalent to the left halves of the letters.

Question 7.
State two differences between a convex and a concave lens.
Solution:

 S.No. Convex Lens Concave Lens 1. Thick at middle, thin at edge. Thin at middle, thick at edge. 2. Can form real image. Cannot form real image.

Question 8.
Give one use each of a concave and a convex mirror.
Solution:
Use of concave mirror: Doctors use concave mirrors for examining eyes, ears, nose, throat, and teeth.
Use of convex mirror: A convex mirror is used as a side view mirror in motor vehicles.

Question 9.
Which type of mirror can form a real image?
Solution:
Concave.

Question 10.
Which type of lens forms always a virtual image?
Solution:
Concave.

Choose the correct option in questions 11-13

Question 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
Solution:
(ii) Concave mirror.

Question 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) 3 m
(ii) 5 m
(iii) 6 m
(iv) 8 m
Solution:
(iii) 6 m

Question 13.
The rearview mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rearview 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) 1 m/s
(ii) 2 m/s
(iii) 4 m/s
(iv) 8 m/s
Solution:
(iii) 4 m/s

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