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A. Choose the correct option.

1. A mirror that always produces a virtual, upright image of the same size as the object is a spherical mirror
   a. convex mirror
   b. convex mirror
   c. plane mirror
   d. concave mirror
   Answer: c. plane mirror
2. A convex mirror produces
   a. real and upright images
   b. real and enlarged images
   c. virtual and diminished images
   d. virtual and enlarged images
   Answer: c. virtual and diminished images
3. A magnifying glass is a
   a. convex mirror
   b. convex lens
   c. concave mirror
   d. concave lens
   Answer: b. convex lens
4. Car wing mirrors are
   a. concave mirrors
   b. convex mirrors
   c. plane mirrors
   d. concave lenses
   Answer: b. convex mirrors

B. Fill in the blanks with the correct words.

1. An image that cannot be formed on a screen is called a virtual image.
2. An image that can be formed on a screen is called a real image.
3. A convex mirror always forms diminished, virtual images.
4. A concave lens always forms diminished, virtual images.
5. White light is made of seven colours.

C. Write T for true and F for false.

1. Usually light travels in straight lines. T
2. A rough surface reflects a parallel beam of light in a single direction. F (A rough surface reflects light in many directions, which is diffuse reflection.)
3. A virtual image can be formed on a screen or be touched. F (A virtual image cannot be obtained on a screen.)
4. In a concave mirror the reflecting surface is the inner surface of the sphere. T
5. Concave lenses are used to make reading glasses. F (Convex lenses are used for reading glasses to correct long-sightedness. Concave lenses are used for short-sightedness.)

D. Answer the following questions.

1. Can we see a source of light through a bent tube? Explain your answer.

Answer: No, we cannot see a source of light through a bent tube. This is because light generally travels in straight lines, a property known as rectilinear propagation. The light rays from the source cannot bend around the curves in the tube to reach our eyes.

• Write down the characteristics of images formed by a plane mirror.
  Answer: The image formed by a plane mirror is:
  • Virtual (cannot be projected on a screen)
  • Upright (erect)
  • Of the same size as the object
  • Laterally inverted (left and right are reversed)
  • Located as far behind the mirror as the object is in front of it.
• Differentiate between real and virtual images.
  Answer:

Real Image	Virtual Image
Formed by the actual convergence of light rays.	Formed when light rays appear to diverge from a point.
Can be obtained on a screen.	Cannot be obtained on a screen.
Is always inverted.	Is always erect.

4.Write down three uses of curved mirrors.
Answer: Curved mirrors, which include both concave and convex types, have several important applications in daily life and technology. Here are three key uses:

Concave Mirrors: Used as shaving mirrors, dentist’s mirrors, and in reflecting telescopes and solar cookers.

Convex Mirrors: Used as rear-view mirrors in vehicles and for security in shops and at blind corners in buildings.

Concave Mirrors in Solar Cookers and Telescopes:
Concave mirrors are used to concentrate light and heat. In solar cookers, they reflect and focus sunlight onto a single point, generating high temperatures for cooking. In reflecting telescopes (like Newtonian telescopes), large concave mirrors are used to gather and focus light from distant celestial objects, creating a clear and magnified image for observation.

5.Why are concave mirrors used as dentist’s mirrors?
Answer: Concave mirrors are used as dentist’s mirrors because when the object (a tooth) is placed within the mirror’s focal point, it produces a virtual, erect, and magnified image. This magnification helps the dentist see a detailed, enlarged view of the tooth.

6.Would you use a convex or a concave lens if you want to focus the Sun’s rays to a point?
Answer: You would use a convex lens. A convex lens converges parallel rays of light from the sun to a single point called the focus.

7.How can we make a band of colours from white light? What is this band of colours called?

Answer: We can make a band of colours from white light by passing it through a glass prism. This band of colours is called a spectrum. The colours are Violet, Indigo, Blue, Green, Yellow, Orange, and Red (often remembered as VIBGYOR).

8.Explain an activity to show how can we make a coloured disc white.

Answer:
Activity: Take a circular cardboard disc and divide it into seven equal sectors. Colour these sectors with the seven colours of the spectrum: Violet, Indigo, Blue, Green, Yellow, Orange, and Red. This disc is called Newton’s Disc. Push a pencil through the centre of the disc to act as an axle. Now, spin the disc rapidly. As the disc spins, the seven colours blend due to the persistence of vision, and the disc appears white. This demonstrates that white light is a combination of seven colours.