Advertisements
Advertisements
प्रश्न
The near vision of an average person is 25 cm. To view an object with an angular magnification of 10, what should be the power of the microscope?
Advertisements
उत्तर
It is given, that least distance of distinct vision of an average person (i.e., D) is 25 cm, in order to view an object with magnification 10,
Here, v = D = 25 cm and u = f
But the magnification `m = v/u = D/f`
⇒ `f = D/m = 25/10` = 2.5 cm = 0.025 m
But power `P = 1/(f("in" m)) = 1/0.025` = 40 D
This is the required power of lens.
APPEARS IN
संबंधित प्रश्न
Explain the basic differences between the construction and working of a telescope and a microscope
If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens ? the diameter of the moon is 3.48 × 106 m and the radius of lunar orbit is 3.8 × 108m.
Magnifying power of a simple microscope is inversely proportional to the focal length of the lens. What then stops us from using a convex lens of smaller and smaller focal length and achieving greater and greater magnifying power?
You are given the following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct a compound microscope?
| Lenses | Power (D) | Aperture (cm) |
| L1 | 3 | 8 |
| L2 | 6 | 1 |
| L3 | 10 | 1 |
Draw a ray diagram showing image formation in a compound microscope ?
Suggest two ways by which the resolving power of a microscope can be increased?
A compound microscope uses an objective lens of focal length 4 cm and eyepiece lens of focal length 10 cm. An object is placed at 6 cm from the objective lens. Calculate the magnifying power of the compound microscope. Also calculate the length of the microscope.
Draw the labelled ray diagram for the formation of image by a compound microscope.
Derive the expression for the total magnification of a compound microscope. Explain why both the objective and the eyepiece of a compound microscope must have short focal lengths.
An object is placed at a distance u from a simple microscope of focal length f. The angular magnification obtained depends
Consider the following two statements :-
(A) Line spectra contain information about atoms.
(B) Band spectra contain information about molecules.
A simple microscope using a single lens often shows coloured image of a white source. Why?
An eye can distinguish between two points of an object if they are separated by more than 0.22 mm when the object is placed at 25 cm from the eye. The object is now seen by a compound microscope having a 20 D objective and 10 D eyepiece separated by a distance of 20 cm. The final image is formed at 25 cm from the eye. What is the minimum separation between two points of the object which can now be distinguished?
Define the magnifying power of a microscope in terms of visual angle.
What is the advantage of a compound microscope over a simple microscope?
A convex lens of a focal length 5 cm is used as a simple microscope. Where should an object be placed so that the image formed by it lies at the least distance of distinct vision (D = 25 cm)?
Draw a ray diagram of compound microscope for the final image formed at least distance of distinct vision?
An angular magnification of 30X is desired using an objective of focal length 1.25 cm and an eye piece of focal length 5 cm. How will you set up the compound microscope for the final image formed at least distance of distinct vision?
The focal lengths of the objective and the eye-piece of a compound microscope are 1.0 cm and 2.5 cm respectively. Find the tube length of the microscope for obtaining a magnification of 300.
What is meant by a microscope in normal use?
