Tag: physics

Questions Related to physics

In an astronomical telescope, the intermediate image is

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. virtual, erect and magnified

  2. real, erect and magnified

  3. real, inverted and reduced

  4. virual, inverted and reduced

Show answer
Correct Option: C
Explanation:

Astronomical telescope in which the image is inverted$,$ is n of the two principle types of the telescopes$.$ Its primary function is to enlarge the retinal image of a distant object$.$

hence,
option $(C)$ is correct answer.

Magnifying power of an astronomical telescope is 15. Then ratio of the focal length of the objective to the focal length length of the eye piece is

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. $15$

  2. $\cfrac 1 {15}$

  3. $11.5$

  4. $None$

Show answer
Correct Option: B

In a terrestrial telescope the focal length erecting lens is $20cm$. The length of the telescope $96cm$ . If the magnifying power of the telescope $10$. Then the focal length of eye -piece and objective are respectively 

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. $8cm,80cm$

  2. $\dfrac{96}{11}cm,\dfrac{960}{11}cm$

  3. $6cm,90cm$

  4. None of these

Show answer
Correct Option: D

The aperture of the largest telescope in the world is $5 m,$ if the separation between the Moon and the Earth is $4 \times 10^5 km$ and the wavelength of the visible light is $5000 \overset {o}{A}$ then the minimum separation between the objects on the surface of the Moon which can be just resolve is approximately

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. $1 m$

  2. $10 m$

  3. $50 m$

  4. $200 m$

Show answer
Correct Option: A

If an astronomical telescope has objective and eye-pieces of focal length 200 cm and 4 cm respectively,then the magnifying power of the telescope for the normal vision is:

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. 42

  2. 50

  3. 58

  4. 204

Show answer
Correct Option: C
Explanation:

 

It is given that,

Focal length of eye- piece fe = 4 cm

Focal length of object is fo = 200 cm

Least distance of distinct vision is d = 25 cm

So, magnifying power of microscope is

$ M=\dfrac{-{{f} _{0}}}{{{f} _{e}}}\left( 1+\dfrac{{{f} _{e}}}{d} \right) $

$ M=\dfrac{-200}{4}\left( 1+\dfrac{4}{25} \right) $

$ =-58\,cm $

 

Focal lengths of the objective lens and eye-piece of an astronomical telescope are $2m$ and $0.05m$. Find the length of telescope in normal adjustment.

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. $1.05 \mathrm { m }$

  2. $1.16 \mathrm { m }$

  3. $2.05 m$

  4. $2 \mathrm { gm }$

Show answer
Correct Option: A

The diameter of moon is $3.5\times{10}^{3}km$ and its distance from the earth is $3.8\times{10}^{5}km$. The focal length of the objective and eyepiece are $4m$ and $10cm$ respectively. The angle subtended by the diameter of the image of the moon will be approximately

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. ${2}^{o}$

  2. ${20}^{o}$

  3. ${40}^{o}$

  4. ${50}^{o}$

Show answer
Correct Option: B

The magnifying power an astronomical telescope for normal adjustment is -

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. $- \frac{f _0}{f _e}$

  2. $-f _0 \times f _e$

  3. $- \frac{f _e}{f _0}$

  4. $-f _0 + f _e$

Show answer
Correct Option: A

If for a given telescope $D = 22 \,mm$ and $\lambda = 6 \times 10^{-7}m$, then the minimum value of the angle subtended by two stars that could be resolved is approximately:

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. $0.4 \times 10^{-7} rad$

  2. $0.8 \times 10^{-7} rad$

  3. $4 \times 10^{-6} rad$

  4. $8 \times 10^{-6} rad$

Show answer
Correct Option: C

The focal length of objective of an astronomical telescope is $1m$. If the magnifying power of telescope is $8$, then what is length of telescope for relaxed eye?

physics observing space: telescopes space research and satellites space travel space exploration and forms of light

  1. $85cm$

  2. $95cm$

  3. $105cm$

  4. $20cm$

Show answer
Correct Option: D