Tag: radio telescope and space telescopes

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Questions Related to radio telescope and space telescopes

Multiple choice physics satellite launch vehicles rocket propellants universe and space science xx radio telescope and space telescopes launching vehicles

Blow a balloon and let it go. You will find it moving in the direction opposite to the direction in which the air is ejected. This demonstrates :

  1. the principle of rocket propulsion

  2. the principle of combustion

  3. the principle of conservation of energy

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of rocket propulsion works on the 'Newton's Third Law of Motion'. It states that, 'to every action, there is always an equal and opposite reaction'.

In the case of a rocket, the engine emits hot burning gases in the downward direction. These gases apply an equal and opposite reaction force to the rocket in the upward direction.
This is how a rocket is propelled.
Rocket propulsion is similar to the example of the situation in which, if we blow a balloon and let it go, it starts moving in the direction opposite to the direction in which the air is ejected. 
Balloon forces out the air inside it. The air applies an equal and opposite reaction force to the balloon.

Multiple choice physics satellite launch vehicles rocket propellants universe and space science xx radio telescope and space telescopes launching vehicles

The scientific instrument which is usually placed in the front region of the rocket is called :

  1. PAYBOOK

  2. PLAYOAD

  3. PAYLOAD

  4. PLAYWOOD
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The scientific instrument placed in the front region of the rocket is called PAYLOAD. For a rocket payload can be a satellite, space probe or a space craft carrying humans. The fraction of payload to the total liftoff weight of the rocket iscalled as palyload friction.

Multiple choice physics satellite launch vehicles rocket propellants universe and space science xx radio telescope and space telescopes launching vehicles

The principle of rocket propulsion depends on :

  1. Newton's third law of motion

  2. Principle of conservation of momentum

  3. Either A and B

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The principle of rocket propulsion works on the 'Newton's Third Law of Motion'. It states that, 'to every action, there is always an equal and opposite reaction'.

In the case of a rocket, the engine emits hot burning gases in the downward direction. These gases apply an equal and opposite reaction force to the rocket in the upward direction.
This is how a rocket is propelled.
The principle of conservation of momentum states that whenever two bodies collide or get separated, then their  total momentum before collision or separation is equal to their total momentum after collision or separation.
Since the gases of the rocket and the rocket are stationery at the start, their total momentum is zero. After the gases start burning, the momentum imparted to the rocket is equal and opposite to that of the gases. Hence their total momentum is zero.

Multiple choice physics option c: imaging optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes

A reflecting telescope has a large mirror for its objective with radius of curvature equal to 80 cm. The magnifying power of this telescope if eye piece used has a focal length of 1.6 cm is:

  1. 100

  2. 50

  3. 25

  4. 5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The focal length of objective mirror $f _0 = \dfrac{R}{2} = \dfrac{80}{2} = 40 \,cm$
and focal length of eye piece = 1.6 cm
$\therefore $ magnifying power, $m = \dfrac{f _0}{f _e} = \dfrac{40}{1.6 } = 25$

Multiple choice physics option c: imaging optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes

A telescope is used to resolve two stars separated by $4.6 \, \times \, 10^{-6}$ rad. If the wavelength of light used is 5460 $\overset{0}{A}$, what should be the aperture of the objective of the telescope? 

  1. 0.1488 m

  2. 0.567 m

  3. 1 m

  4. 2 m
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Aperature of the telescope, $D = \dfrac{1.22\lambda}{d\theta}$ 


Here, $\lambda = 5460\ \overset{0}{A} = 5460 \times 10^{-10}m$


$ d\theta= 4.6 \times10^{-6}\ rad$

$\therefore D = \dfrac{1.22\times5460\times10^{-10}}{4.6\times 10^{-6}}$
$ = 0.1488m $

Multiple choice physics option c: imaging optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes

If you want to make Refracting Telescope, what components will you choose ?

  1. One convex led and one concave lens.

  2. Two convex lenses.

  3. One concave mirror, one plane mirror and one convex lens.

  4. Once concave mirror, one convex mirror and one convex lens.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A refracting telescope uses two convex lenses: an objective lens to gather light and an eyepiece lens to magnify the image.

Multiple choice physics option c: imaging optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes
Which material should be chosen to make the concave mirrors of a high resolution telescope so that it can also withstand temperature variations?

  1. Quartz

  2. Flint glass

  3. Crown glass

  4. Combination of Flint and Silica
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Quartz makes an ideal mirror. Its high hardness results in the smoothest micropolished surface possible, and its thermal dimensional stability allows the optician to produce a flat surface with almost no edge defects.

Multiple choice physics option c: imaging optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes

Scientists identify the elements that are burning in the stars by using which of the following devices?

  1. Refractive telescopes

  2. Reflective telescopes

  3. Spectroscopes

  4. Polarimeters

  5. Photoelectric mircoscopes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Using the spectroscope, scientists can separate the individual line spectra of the elements that are burning in the stars and therefore identify the elements.
Multiple choice physics option c: imaging optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes

In an astronomical telescope of refracting type:

  1. Eyepiece has greater focal length

  2. Objective has greater focal length

  3. Objective and eyepiece have equal focal length

  4. Eyepiece has greater aperture than the objective
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An astronomical telescope of refracting type has objective of greater focal length to have more surface area for incoming light from celestial bodies.