Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

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. 

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

Four lenses of focal length $+15cm,+20cm,+150cm$ and $+250cm$ are available for making an astronomical telescope. To produce the largest magnification, the focal length of the eyepiece should be

  1. $+15cm$

  2. $+20cm$

  3. $+150cm$

  4. $+250cm$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In astronomical telescope, magnification is inversely proportional to focal length of eye piece. Hence, it will be minimum i.e. +15cm as in question.

Multiple choice physics observing space: telescopes optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes

A reflecting telescope utilises :

  1. a convex mirror

  2. a concave mirror

  3. a prism

  4. a plano-concave lens
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Unlike convex mirrors, concave mirrors show different image types depending on the distance between the object and the mirror. That is why a reflecting telescope utilizes a concave mirror. If you observe the design of a reflecting telescope, it uses the incoming rays to focus through a concave mirror to focus on the second mirror which in turn sends the rays to the eye-piece. So, the concave mirror is intrinsic to the design of a reflecting telescope.

Multiple choice physics observing space: telescopes optical instruments : telescope the reflecting telescope optical telescope xx radio telescope and space telescopes

This question has Statement-1 and Statement-2. Of the four choices given after the Statements, choose the one that best describes the two Statements.
Statement 1 : Very large size telescopes are reflecting telescopes instead of refracting telescopes.
Statement 2 : It is easier to provide mechanical support to large size mirrors than large size lenses.

  1. Statement-1 is true and Statement-1 is false and statement-2 is true

  2. Statement-1 is false and Statement-2 is true

  3. Statements-1 and Statement-2 are true and Statement-2 is correct explanation for Statement-1

  4. Statements-1 and Statements-2 are true and Statement-2 is not the correct explanation for Statement-1
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Large telescopes are reflecting telescopes because mirrors are easier to support from the back, whereas lenses must be supported at the edges, which causes sagging in large sizes.