Ch 15 : Light

                                                                                      Light

Question: 1 - Fill in the blanks:

1. An image that cannot be obtained on a screen is called ____________.
   
   Answer: Virtual
   
2. Image formed by a convex __________ is always virtual and smaller in size.
   
   Answer: Mirror
   
3. An image formed by a __________ mirror is always of the same size as that of the object.
   
   Answer: Plane
   
   
4. An image which can be obtained on a screen is called a _________ image.
   
   Answer: Real
   
   
5. An image formed by a concave ___________ cannot be obtained on a screen.
   
   Answer: 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.
   (F)
2. A concave lens always form a virtual image.
   (T)
3. We can obtain a real, enlarged and inverted image by a concave mirror.
   (F)
4. A real image cannot be obtained on a screen.
   (F)
5. A concave mirror always form a real image.
   (F)

Question: 3 -Match the items given in Column I with one or more items of Column II.
Question: 4 -State the characteristics of the image formed by a plane mirror.

Answer: In case of plane mirror, the image is erect, virtual and of same size as the object.

Question: 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.

Answer: Some examples: A, H, I, M, O, T, U, V, W and X

Question: 6 -What is a virtual image? Give one situation where a virtual image is formed.

Answer: The image which cannot be obtained on a screen is called virtual image. For example, virtual image is always formed in case of plane mirror and convex mirror.

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

Answer: A convex lens can make enlarged image, while a concave lens would always make smaller image. A convex lens usually makes real image, while a concave lens always makes a virtual image.

Question: 8 -Give one use each of a concave and a convex mirror.

Answer: (a) Concave mirror is used in solar furnace. (b) Convex mirror is used in rear view mirrors.

Question: 9 -Which type of mirror can form a real image?

Answer: Concave mirror

Question: 10 - Which type of lens forms always a virtual image?

Answer: Concave lens

Choose the correct option in questions 11–13
Question: 11 - A virtual image larger than the object can be produced by a

1. Concave lens
2. Concave mirror
3. Convex mirror
4. Plane mirror

Answer: (c) Concave mirror

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

1. 3 m
2. 5 m
3. 6 m
4. 8 m

Answer: (a) 3 m

Question: 13 -The rear view 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 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

1. 1 m/s
2. 2 m/s
3. 4 m/s
4. 8 m/s

Answer: (b) 2 m/s