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प्रश्न
Observe the following figure and answer the questions.
a) Which optical instrument shows arrangement of lenses as shown in the figure?
b) Write in brief the working of this optical instrument.
c) How can we get different magnifications in this optical instrument?
d) Draw the figure again and labelled it properly
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उत्तर
a) Arrangement of lenses shown in the figure is refracting telescope.
b) 1) object lens collect the light coming form the distant object and forms the image
2)The image works as object for the eye piece which forms the final image.
c) We can get different magnifications by using the eye piece with different focal lengths.
d)
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संबंधित प्रश्न
To determine the approximate focal length of the given convex lens by focussing a distant object (say, a sign board), you try to focus the image of the object on a screen. The image you obtain on the screen is always
(a) erect and laterally inverted
(b) erect and diminished
(c) inverted and diminished
(d) virtual, inverted and diminished
Complete the following table:
| Instrument | Number of Convex Lenses |
Use |
| Simple Microscope | .............. | .............. |
| Compound Microscope | .............. | .............. |
| Telescope | .............. | .............. |
A beam of light travelling in a rectangular glass slab emerges into air. Draw a ray-diagram indicating the change in its path.
Draw a labelled ray diagram to show the angle of incidence and the angle of refraction for a refracted ray of light.
If an object is placed at the focus of a convex lens, where is the image formed?
What type of lens would you use as a magnifying glass? How close must the object be to the lens?
Fill in the following blank with suitable word:
The image in a convex lens depends upon the distance of the ........... from the lens.
If the object is moved to a point only 3 cm away from the lens, what is the new position, height and nature of the image?
How would a pencil look like if you saw it through How would a pencil look like if you saw it through
An object is placed 20 cm from (a) a converging lens, and (b) a diverging lens, of focal length 15 cm. Calculate the image position and magnification in each case.
In a certain murder investigation, it was important to discover whether the victim was long-sighted or short-sighted. How could a detective decide by examining his spectacles?
Study the diagram given below.
- Name the lens LL’.
- What are the points O and O’ called?
- Complete the diagram to form the image of the object AB.
- State the three characteristics of the image.
- Name a device in which this action of lens is used.
The given below figure shows an object OA and its image IB formed by a lens.
If you are to determine to focal length of a convex lens, you should have
(A) a convex lens and a screen
(B) a convex lens and a lens holder
(C) a lens holder, a screen holder and a scale
(D) a convex lens, a screen, holder for them and a scale
State two applications of a convex lens.
_______ is a combination of two convex lenses with small focal length.
Write the name.
The lens used in simple microscope.
Distinguish between Concave lens and Convex lens.
Distinguish between Concave lens and Convex Lens.
Distinguish between Concave lens and Convex Lens.
