Light Class 7 Science Notes - Chapter 15

White light consists of seven colors. The path in which light travels is a straight line. A smooth or shinning surface that forms images by reflection of light is called a mirror. Types of images formed with mirrors –

  • Real image – Images that can be obtained on the screen are called real images. The image formation is in inverted form and occurs due to converging Lens.
  • Virtual image – Images that cannot be obtained on the screen are called virtual images. The image formation is upright and occurs due to diverging Lens.

Plane mirrors form erect images. The size is the same as that of the object and is virtual. Whenever an image is formed by a mirror the right side of the object appears to be on the left side in the image whereas the left side of the object is seen on the right side of the image.

  • Concave mirror – Forms inverted and real image. Whenever an object is placed close to the mirror, the image that will be formed is erect, magnified, and virtual.
  • Convex mirror – The image formed by a convex mirror is virtual, smaller in size, and erect.
  • Convex lens – It forms inverted and real images. Whenever an object is placed close to the lens, the image which is formed is, magnified, virtual, and erect. To see objects in big size or in a magnified form this lens is called magnifying glass.
  • Concave lens – The images formed by the concave lens are always virtual, erect, and smaller than the object.

Few Important Questions

  1. Fill in the blanks-
    1. When an image is not obtained on the screen it is called _________.
    2. Image formed by a concave ___________ will not be obtained on the screen.
    3. Images formed by __________ are smaller in size and virtual.
  1. What are the characteristics of the images that are formed by a plane mirror?
  2. Distinguish between convex and concave mirror.
  3. Virtual images are formed by what type of lens?
  4. Real images are formed by what type of mirrors?
  5. Define a virtual image. Give one example.
  6. When is the virtual image appear larger than the object?
  7. State true or false –
    1. Erect, and enlarged image can be obtained by a convex mirror.
    2. Real images can be obtained on the screen.
    3. A convex lens always forms virtual images.

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Practise This Question

In the rusting of Iron, which of the following cell reactions occurs at the anode?