Tag: space research and satellites

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

The length of an astronomical telescope for normal vision is _______.

  1. $-\displaystyle\frac{f _o}{f _e}$
  2. $-f _o\times f _e$
  3. $\displaystyle\frac{f _e}{f _o}$
  4. $f _o+f _e$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To get a magnified image of an object at infinity the image formed by objective lens will beat focus and if we want maximum magnification then the image formed by objective should be at focus of the eye piece.

Hence length of telescope =${ f } _{ o }+{ f } _{ e }$.
Here ${ f } _{ o }$ and ${ f } _{ e }$ are focal length of objective and eyepiece lens respectively.

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

In which of the following instruments is final image erect?

  1. Simple microscope

  2. Compound microscope

  3. Astronomical telescope

  4. Galilean telescope
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

simple microscope is placed between the optic center and the focus and the image is erect, virtual and magnified.

For compound microscope -The final image is virtual, inverted and magnified.
The final image formed by an astronomical telescope is always virtual, inverted.
Galilean telescope is to produce a virtual, erect image.



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

In which of the following instruments is the final image inverted?

  1. Projector

  2. Camera

  3. Microscope

  4. Telescope
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Explanation
For compound microscope -The final image is virtual, inverted and magnified.
The final image formed by an astronomical telescope is always virtual, inverted.
Camera and projector always form erect image.
Multiple choice physics observing space: telescopes space research and satellites space travel space exploration and forms of light

The final image formed by an astronomical telescope is

  1. real and erect

  2. virtual and erect

  3. real and inverted

  4. virtual and inverted
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An astronomical telescope is an optical instrument which is used to see the magnified image of distant heavenly bodies. The final image formed by an astronomical telescope is always virtual, inverted and magnified.

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

For the astronomical telescope, the focal length of objective lens is ${f} {o}$ and the eye piece lens is ${f} _{e}$. Then the tube length of the telescope is ____

  1. $L\ge { f } _{ o }-{ f } _{ e }$
  2. $L\ge { f } _{ o }+{ f } _{ e }$
  3. $L<{ f } _{ o }+{ f } _{ e }$
  4. $L\le { f } _{ o }-{ f } _{ e }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For astronomical telescope
$\left| { v } _{ 1 } \right| ={ f } _{ o }$
$\left| { u } _{ 2 } \right| \le { f } _{ e }$
Probable answer would be (c) conceptually correct

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

In an astronomical telescope, the intermediate image is

  1. virtual, erect and magnified

  2. real, erect and magnified

  3. real, inverted and reduced

  4. virual, inverted and reduced
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  1. $1 m$
  2. $10 m$
  3. $50 m$
  4. $200 m$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The limit of resolution for a telescope is given by theta = 1.22 * lambda / D, where D is the aperture diameter and lambda is the wavelength. Multiplying this angular resolution by the distance to the moon gives the minimum linear separation, which calculates to approximately 50 meters.

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

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:

  1. 42

  2. 50

  3. 58

  4. 204
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $