Advertisements
Advertisements
प्रश्न
Answer the following question in detail.
Obtain the expressions for magnifying power and the length of an astronomical telescope under normal adjustments.
Advertisements
उत्तर
- For telescopes, α is the visual angle of the object from its own position, which is practically at infinity.
- The visual angle of the final image is β and its position can be adjusted to be at D. However, under normal adjustments, the final image is also at infinity making a greater visual angle than that of the object.
Telescope - The parallax at the cross wires can be avoided by using the telescopes in normal adjustments.
- The objective of focal length fo focusses the parallel incident beam at a distance fo from the objective giving an inverted image AB.
- For normal adjustment, the intermediate image AB forms at the focus of the eye lens. Rays refracted beyond the eye lens form a parallel beam inclined at an angle β with the principal axis.
- Angular magnification or magnifying power for telescope is given by,
M = `β/α≈(tan(β))/(tan(α))=("BA/P"_"e""B")/("BA/P"_"o""B")="f"_"o"/"f"_"e"` - Length of the telescope for normal adjustment is, L = fo + fe.
APPEARS IN
संबंधित प्रश्न
Answer the following question in detail.
What is a terrestrial telescope and an astronomical telescope?
Answer the following question in detail.
What is the limitation in increasing the magnifying powers of the astronomical telescope?
Discuss about simple microscope and obtain the equations for magnification for near point focusing and normal focusing.
What is the near point focusing?
Why is oil-immersed objective preferred in a microscope?
What is the use of an erecting lens in a terrestrial telescope?
What is the use of collimator in a spectrmeter?
What is the remedy of hypermetropia?
What is presbyopia?
What is astigmatism? What is its remedy?
Discuss about simple microscope and obtain the equations for magnification for near point focusing and normal focusing.
Obtain the equation for resolving the power of the microscope.
Discuss about astronomical telescope.
Mention different parts of the spectrometer.
Explain the preliminary adjustments of the spectrometer.
A compound microscope has a magnification of 30. The focal length of eye piece is 5 cm. Assuming the final image to be at least distance of distinct vision, find the magnification produced by the objective.
The near point and the far point for a person are 50 cm and 500 cm, respectively. Calculate the power of the lens the person should wear to read a book held in hand at 25 cm. What maximum distance is clearly visible for the person with this lens on the eye?
There are four convex lenses L1, L2, L3 and L4 of focal length 2, 4, 6 and 8 cm, respectively. Two of these lenses from a telescope of length 10 cm and magnifying power 4. The objective and eye lenses are respectively
When a convex lens of 12.5 cm focal length is used as a magnifying glass, normal eye can see an object clearly at a distance of 25 cm. The magnifying power of the instrument is ____________.
If astronomical telescope of length 1.53 m has magnifying power of magnitude 50, the values of fo and fe are ____________.
The magnifying power of a telescope is nine. When it is adjusted for parallel rays, the distance between the objective and eyepiece is 20 cm. The focal length of objective and eyepiece are respectively.
The magnifying power of a telescope is high if its objective and eyepiece have respectively ______.
A simple microscope is used to see the object first in blue light and then in red light. Due to the change from blue to red light, what is the effect on its magnifying power?
The speed of light in media 'A' and 'B' are 2.0 × 1010 cm/s and 1.5 × 1010 cm/s respectively. A ray of light enters from medium B to A at an incident angle 'θ'. If the ray suffers total internal reflection, then ______.
An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To the observer the tree appears:
The image formed by an objective of a compound microscope is ______.
A camera objective has an aperture diameter of d. If the aperture is reduced to diameter d/2, the exposure time under identical conditions of light should be made ______.
