In order to increase the magnifying power of a compound microscope ____.
the focal lengths of the objective and the eye piece should be small
objective should have small focal length and the eye piece large
both should have large focal lengths
the objective should have large focal length and eye piece should have small
If the focal length of the objective lens is increased then ____.
magnifying power of microscope will increase but that of telescope will decrease
magnifying power of microscope and telescope both will increase
magnifying power of microscope and telescope both will decrease
magnifying power of microscope will decrease but that of telescope will increase
The magnification produced by the objective lens and the eye lens of a compound microscope are 25 and 6 respectively. The magnifying power of this microscope is ____.
19
31
150
The focal lengths of the objective and the eye-piece of a compound microscope are 2.0 cm and 3.0 cm respectively. The distance between the objective and the eye-piece is 15.0 cm. The final image formed by the eye-piece is at infinity. The two lenses are thin. The distances in cm of the object and the image produced by the objective measured from the objective lens are respectively ____.
2.4 and 12.0
2.4 and 15.0
2.3 and 12.0
2.3 and 3.0
Resolving power of a microscope depends upon ____.
the focal length and aperture of the eye lens
the focal lengths of the objective and the eye lens
the apertures of the objective and the eye lens
the wavelength of light illuminating the object
An observer looks at a tree of height 15 m with a telescope of magnifying power 10. To him, the tree appears ____.
10 times taller
15 times taller
10 times nearer
15 times nearer
The focal length of objective and eye lens of a astronomical telescope are respectively 2 m and 5 cm. Final image is formed at (i) least distance of distinct vision (ii) infinity. The magnifying power in both cases is ____.
– 48, – 40
– 40, – 48
– 40, 48
– 48, 40
For observing a cricket match, a binocular is preferred to a terrestrial telescope because ____.
the binocular gives the proper three dimensional view
the binocular has shorter length
the telescope does not give erect image
telescope have chromatic aberrations
To increase the magnifying power of telescope (fo = focal length of the objective and fe = focal length of the eye lens) ____.
fo should be large and fe should be small
fo should be small and fe should be large
fo and fe both should be large
fo and fe both should be small
Relative difference of focal lengths of objective and eye lens in the microscope and telescope is given as ____.
it is equal in both
it is more in telescope
it is more in microscope
it may be more in any one
If the telescope is reversed i.e. seen from the objective side ____.
object will appear very small
object will appear very large
there is no effect on the image formed by the telescope
image is slightly greater than the earlier one
The focal length of the objective of a terrestrial telescope is 80 cm and it is adjusted for parallel rays, then its magnifying power is 20. If the focal length of erecting lens is 20 cm, then full length of telescope is ____.
84 cm
100 cm
124 cm
164 cm
An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The separation between the objective and the eye piece is 36 cm and the final image is formed at infinity. The focal length fo of the objective and the focal length fe of the eye piece are ____.
fo = 45 cm and fe = – 9 cm
fo = 7.2 cm and fe = 5 cm
fo = 50 cm and fe = 10 cm
fo = 30 cm and fe = 6 cm
In an astronomical telescope, the focal lengths of two lenses are 180 cm and 6 cm respectively. In normal adjustment, the magnifying power is ____.
1080
200
30
186
The magnifying power of an astronomical telescope for relaxed vision is 16. On adjusting, the distance between the objective and eye lens is 34 cm. Then the focal length of objective and eye lens is respectively ____.
17 cm, 17 cm
20 cm, 14 cm
32 cm, 2 cm
30 cm, 4 cm
In Galilean telescope, if the powers of an objective and eye lens are respectively +1.25 D and – 20 D, then for relaxed vision, the length and magnification is ____.
21.25 cm and 16
75 cm and 20
75 cm and 16
8.5 cm and 21.25
The aperture of a telescope is made large, because ____.
to increase the intensity of image
to decrease the intensity of image
to have greater magnification
to have lesser resolution
In Galilean telescope, the final image formed is ____.
real, erect and enlarged
virtual, erect and enlarged
real, inverted and enlarged
virtual, inverted and enlarged
The magnifying power of a telescope is 9. When it is adjusted for parallel rays, the distance between the objective and the eye-piece is found to be 20 cm. The focal length of the two lenses is ____.
18 cm, 2 cm
11 cm, 9 cm
10 cm, 10 cm
15 cm, 5 cm
The focal length of the objective and eye piece of a telescope is respectively 60 cm and 10 cm. The magnitude of the magnifying power when the image is formed at infinity is ____.
50
6
70
5