Science prep. (3)

Complete the following:

  1. The optical piece which forms equal reversed image to the body is ------.
  2. The Roman use a huge ------to burn the sail boats of enemies’ ships by usage of sunlight.
  3. The image of body formed behind the plane mirror is always ------, ------and ------.
  4. The focal length of a concave mirror equals 10 cm, to obtain a virtual image; the body is placed at a distance from the mirror pole equals ------.
  5. A concave lens is placed in the passage of sun rays a very small image for the sun is formed at a distance from the optical center of the lens, if this lens is used to form equal image for a body, the distance between the body and the optical centre of the lens is ------cm.
  6. Lens is placed in the passage of the sun rays, a very small image is formed at a distance 10 cm from the optical center, the same lens is used to obtain virtual, enlarged, and erect image of a body (a), which is at distance ------cm from the optical center.
  7. In a lens the radius of curvature equals 20 cm, so its focal lens equals ------cm.
  8. The phenomenon of the light bouncing off in the same medium when it meets the reflecting surface is called ------.
  9. The point that is in the middle of the reflecting surface of the concave mirror is called ------.
  10. ------is the image which can be received on a screen.
  11. The incident light ray parallel to the principle axis of the concave mirror it will reflect passing through ------.
  12. If the light ray falls passing through the focus of the concave mirror it will reflect ------to the main axis.
  13. A concave mirror with a focal length of 20 cm and the object is placed at a distance of 50 cm from the mirror, the image formed at distance ------than 40 cm.
  14. A spherical mirror where its radius is 60 cm, its focal length equals ------cm.
  15. When the object is at the center of curvature of a concave mirror, the image is ------, ------, and ------.
  16. The focal length of the concave lens equals the distance between ------and ------.
  17. The concave lens ------the rays falling on it.
  18. The focal lens of a convex lens equals 10 cm, the half radius of surface is ------cm.
  19. The short sighted person needs a medical eye glasses with ------lenses.
  20. The vision detect which is due to a shortness in the radius of the eye sphere is called ------.
  21. If a light ray falls passing through the optical center of the convex lens it leaves the lens ------.
  22. A convex lens with a focal length of 20 cm, and an object was placed 40 cm from the lens, the image of the object is formed at ------.
  23. An object when placed at a distance less than the focal length of the convex lens, the characteristics of the image formed are ------, ------, and ------.
  24. The image formed by using a concave lens is ------, ------, and ------.
  25. The point that is in the middle of the reflective surface of the concave mirror is called ------.
  26. The straight line that passes by the pole of the mirror and its spherical center is ------.
  27. The distance between the focus of the concave mirror and its poles is called ------.
  28. A convex mirror has a focal length 20 cm, then half the radius of its spherical surface equals ------.
  29. A long sighted person needs a medical eye glasses with a ------lens.
  30. The angle of incidence = ------.

Give Reason of the following:

  1. The short sighted person requires medical glasses with concave lenses.
  2. The perpendicular incident light ray on the plane mirror reflects on itself.
  3. The focal length of the thick convex length is less than the thin convex lens.
  4. The concave length is used in treatment of the short sightedness.
  5. The convex length is used in treatment of the long sightedness.
  6. The object that is placed at the focus of a convex lens doesn’t form an image of it.
  7. The collective lens has two foci but the collective mirror has one focus.
  8. Most of the people can’t write by the correct way while they are seeing their writings through plane mirror.
  9. It is possible to obtain real image by using concave mirror only.
  10. The spherical mirror has only one principle axis.

Answer the following:

  1. A convex lens its focal length equals 4 cm. an object is placed at a distance of 6 cm from the lens determine the position of the formed image and its characteristics by drawing only two rays.
  2. Compare between long sight and short sight from the following points:
  1. The type of lens used in treatment of each one.
  2. The cause of each one.

Point of comparison / Short sight / Long sight
The type of lens:
The cause:
  1. Show by drawing how to obtain virtual, erect, and enlarged?
  2. Explain only by drawing the formation of image equal to the object by mean of convex lens.
  3. Mention the position and properties of the image formed of an object by means of a convex lens in each of the following cases:
  1. The object is at a distance larger than the focal length and smaller than twice the focal lens.
  2. The object is at a distance equal to twice the focal length.
  1. Draw a diagram to illustrate the image formed when the object at a distance more than double focal length of concave mirror.
  2. A convex lens with a focal length of 10 cm, an object was placed at a distance of 20 cm from the lens. Assign the distance of the object’s image from the lens and mention its properties.

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