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प्रश्न
What is optical centre of a thin lens? Draw diagram/diagrams to illustrate it.
उत्तर
The optical centre of a thin lens is a point O on the principal axis of the lens such that a ray of light directed towards it, passes undeviated and undisplaced from the lens. The diagram illustrating it in a convex and a concave lens are shown alongside.
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संबंधित प्रश्न
A ray of light incident at a point on the principal axis of a convex lens passes undeviated through the lens.
- What special name is given to this point on the principal axis?
- Draw a labelled diagram to support your answer in part (a).
Define the term principal foci of a convex lens and illustrate your answer with the aid of proper diagrams.
Define the term principal foci of a concave lens and show them with the help of proper diagrams.
A ray of light after refraction through a convex lens emerges parallel to principal axis.
- Draw a ray diagram to show it.
- The incident ray passes through a point F on the principal axis. Name the point F.
A beam of light incident on a thin concave lens parallel to its principal axis diverges and appears to come from a point F on the principal axis. Name the point F. Draw a ray diagram to show it.
What do you mean by focal plane of a lens?
If half part of a convex lens is covered, the focal length ______ change, but the intensity of image ______.
What is the path of the ray, after refraction, that passes through the first focus of the lens?
To obtain a magnification of +2 with a concave mirror of radius of curvature 60 cm the object distance must be ______.
What will happen to the focal length of the lens if a part of the lens is covered with an opaque paper?
