Tag: observing space: telescopes

Questions Related to observing space: telescopes

Choose the correct answer from the alternatives given.
Which of the following ray are not electromagnetic waves

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

  1. X-rays

  2. $\gamma- $ rays

  3. $\beta -$ rays

  4. Heat rays

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Correct Option: C
Explanation:

Cosmic rays, γ-rays, and X-rays are part of electromagnetic spectrum, while β-rays are emitted by radioactive elements. Hence β-rays is not electromagnetic waves.

The image of a distant object as seen through an astronomical telescope is

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

  1. Erect

  2. Inverted

  3. Disorted

  4. None

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Correct Option: B
Explanation:

Astronomical telescopes uses convex lenses which form real and inverted image of object at infinite distance.

The large aperture of telescope are used for

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

  1. Greater magnification

  2. Greater resolution

  3. Reducing lens aberration

  4. Case ofmanufacture

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Correct Option: B
Explanation:

Telescopes objective lenses have large apertures so that more number of light rays coming from object should enter and have greater resolution.

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

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

  1. $-\displaystyle\frac{f _o}{f _e}$

  2. $-f _o\times f _e$

  3. $\displaystyle\frac{f _e}{f _o}$

  4. $f _o+f _e$

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Correct Option: D
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.

In which of the following instruments is final image erect?

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

  1. Simple microscope

  2. Compound microscope

  3. Astronomical telescope

  4. Galilean telescope

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Correct Option: A,D
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.



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

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

  1. Projector

  2. Camera

  3. Microscope

  4. Telescope

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Correct Option: C,D
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.

The final image formed by an astronomical telescope is

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

  1. real and erect

  2. virtual and erect

  3. real and inverted

  4. virtual and inverted

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Correct Option: D
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.

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 ____

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

  1. $L\ge { f } _{ o }-{ f } _{ e }$

  2. $L\ge { f } _{ o }+{ f } _{ e }$

  3. $L<{ f } _{ o }+{ f } _{ e }$

  4. $L\le { f } _{ o }-{ f } _{ e }$

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Correct Option: B
Explanation:

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

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

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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. $None$

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Correct Option: B