Advertisements
Advertisements
प्रश्न
Answer the following question.
An optical instrument uses a lens of 100 D for the objective lens and 50 D for its eyepiece. When the tube length is kept at 20 cm, the final image is formed at infinity.
(a) Identify the optical instrument.
(b) Calculate the magnification produced by the instrument.
Advertisements
उत्तर
(a) Power of lens = `1/"focal length"`
So, focal length of objective lens = `1/100 "m" = 1 "cm"`
focal length of eye piece = `1/50 "m" = 2 "cm"`
Since the objective has a smaller focal length than the eyepiece, the instrument is a Compound Microscope.
(b) Magnification produced when the image is formed at infinity is given by, m = `(("L")/("f"_0)) (("D")/("f"_"e"))` where L is the tube length.
So, m = `(20xx25)/(1xx2) = 250`
APPEARS IN
संबंधित प्रश्न
The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall 3 m away by means of a large convex lens. What is the maximum possible focal length of the lens required for the purpose?
A card sheet divided into squares each of size 1 mm2 is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 9 cm) held close to the eye.
- What is the magnification produced by the lens? How much is the area of each square in the virtual image?
- What is the angular magnification (magnifying power) of the lens?
- Is the magnification in (a) equal to the magnifying power in (b)? Explain.
A small piece of wood is floating on the surface of a 2.5 m deep lake. Where does the shadow form on the bottom when the sum is just setting? Refractive index of water = 4/3.
An unsymmetrical double convex thin lens forms the image of a point object on its axis. Will the position of the image change if the lens is reversed?
In the given figure the radius of curvature of the curved face in the planoconvex and the planoconcave lens is 15 cm each. The refractive index of the material of the lenses is 1.5. Find the final position of the image formed.
Show that the least possible distance between an object and its real image in a convex lens is 4f, where f is the focal length of the lens.
A ray parallel to the principal axis, after refraction through a concave lens, appears to diverge from:
A ray passing through the principal focus of a convex lens, after refraction, emerges:
If the refractive index of a liquid equals that of a glass lens (\[n_1 = n_2\]), the lens maker relation gives \[\frac{1}{f} = 0\]. This means the focal length of the lens becomes:
A lens with an infinite focal length behaves like:
