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प्रश्न
A simple microscope is used by watch repairers. Give reason.
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उत्तर
When an object is placed within the focal length of a simple microscope, its magnified and erect image is obtained on the same side of the lens as that of the object. So, a watch repairer sees the minute parts of a watch very clearly with a simple microscope by adjusting the distance between the object and the lens. This helps in repairing the watch. Hence, a simple microscope is used by watch repairers.
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संबंधित प्रश्न
Explain the following term related to spherical lenses:- centres of curvature
Match the items given in Column I with one or more items of Column II.
| Column I | Column II | ||
| (a) | A plane mirror | (i) | Used as a magnifying glass. |
| (b) | A convex mirror | (ii) | Can form image of objects spread over a large area. |
| (c) | A convex lens | (iii) | Used by dentists to see enlarged image of teeth. |
| (d) | A concave mirror | (iv) | The image is always inverted and magnified. |
| (e) | A concave lens | (v) | The image is erect and of the same size as the object. |
| (vi) | The image is erect and smaller in size than the object. |
Complete the following sentence:
All the distances are measured from the .......... of a spherical mirror.
Write the mirror formula. Give the meaning of each symbol which occurs in it.
What do you understand by the focus and focal length of a spherical mirror? Show them on the separate diagrams for each of a concave mirror and a convex mirror.
Define the following terms in the context of spherical mirrors :
(i) Pole
(ii) Centre of curvature
(iii) Radius of curvature
(iv) Principal axis
The letters on the front of an ambulance are written laterally inverted like 
. Give reason.
Does the mirror mentioned in part (b) form real image for all locations of the object?
Name the kind of mirror used to obtain:
A real and diminished image.
A concave mirror forms a virtual image of size twice that of the object placed at a distance 5 cm from it. Find:
- the focal length of the mirror
- position of image
A concave mirror forms a real image of an object placed in front of it at a distance 30 cm, of size three times the size of object. Find
- the focal length of mirror
- position of image.
An object of length 4 cm is placed in front of a concave mirror at distance 30 cm. The focal length of mirror is 15 cm.
- Where will the image form?
- What will be the length of image?
Define the following term in relation to concave mirror.
Principal focus
Define the following term in relation to concave mirror.
Radius of curvature
What is the relation between focal length and radius of curvature of a concave mirror?
Define the term Focus of a concave mirror.
Numerical problem.
The radius of curvature of a spherical mirror is 25 cm. Find its focal length.
