Skip to main content

Lens, Mirror and Telescope

 Lecture 11 Lens, Mirror and Telescope


Lens

An optical tool that converges and diverges a light beam by refraction. Lenses are of mainly two types called concave and convex.



Mirror

Polished and smooth reflecting surface with two types- plain mirror and spherical mirror. 

Spherical mirror have the spherical reflecting surface and are of two types- concave mirrors and convex mirrors.



Telescope

Device used to observe distant things by gathering electromagnetic radiation like visible light, UV wave, X ray etc.

Types of telescopes(Based on location) 

  • Ground based telescope- Telescope installed on earth surface. 
  • Space based telescop- Atmosphere is opaque for most of the electromagnetic spectrum, only a few bands can be observed from the Earth's surface. So for telescope with operating frequency higher than visible light are installed in space only. For visible light and lower frequency telescope can be installed either at ground or space with space based telescope have advantage of no atmospheric interference. 


Types of telescopes(Based on operating frequency) 

  • Gamma ray telescope(Space based) 
  • X ray telescope(Space based) 
  • UV telescope(Space based) 
  • Visible light telescope(Space & Ground based)- three type 1. Reflecting(Mirror based) 2. Refracting(Lense based) 3. Catadioptric/Compound(Lens + Mirror based) 
  • Infrared telescope(Space & Ground based) 
  • Microwave telescope(Space & Ground based) 
  • Radio wave telescope(Space & Ground based) 

 

Major Telescope around the world

Square Kilometre Array(Radio telescope)- A global effort to construct the Square Kilometre Array(SKA) with rays collecting area larger than one square kilometre(one million square metres). SKA is installed at Australia and South Africa. 

Thirty Meter Telescope(Visible light)- Largest visible light telescopes in the world with a 30 m prime mirror diameter installed with collaboration of many countries at Mauna Kea, Hawaii. 


Hubble Space Telescope(Visible light)- The first optical telescope installed by NASA in the space was Hubble with operating frequency of viable and UV light. 

James Webb Space Telescope(Infrared)- Successor of Hubble Space Telescope with operating frequency of Infrared and installed at Sun Earth L2 orbit. 

Chandra X ray Observatory(X ray)- Chandra is the world’s most powerful X ray telescope launched by NASA. Chandra, named for Indian-American physicist Subrahmanyan Chandrasekhar.


Major Telescope in India

ARIES telescope(Visible light)-  A joint collaboration between Indian, Russian, and Belgian scientists. The telescope is located at Devasthal, Nainital at a height of 2,500 metres. 

Astrosat(Multi wavelength)- India’s first space telescope operating as multi-wavelength space telescope.

PRATUSH space telescope(radio telescope)- PRATUSH is a radio telescope designed to be placed on the far side of the moon. It is built by Raman Research Institute(RRI), Bengaluru and Indian Space Research Organisation(ISRO). Aims to uncover the timing and characteristics of the first star formation in the universe, including the colour of the light during Cosmic Dawn.




Table of Contents                                             Lecture 12

Labels:

Comments

Post a Comment

Popular posts from this blog

The Archadian

Every Archadian were looking towards the sky in the hope of sunset and with every passing moment they were afraid of lose. Their fear made them more weak and they lost more life in battle field in-front of large Valvan army. The field was full of blood surrounded by hill on one side and forests from another side. Rest of the two sides covered with two army in front of each other. Archadian vs Valvan The Valvan get more aggressive with their swords flying in the battle field. Finally with sunset, drum sound spread all over the field and war was at end. With sunset over the hills, darkness spread in the field and blood became more red in absence of sun. Alkan, the arrogant Valavn king, ask his solider to return back to tent leaving behind injured and dead Valvan solider in field. Both the army headed towards their tent leaving blood on the earth of Archadians. The Valvan get busy in celebrating their victory in today's battle field. While in Archadian tent, king Arithm order a
Post a Comment
Read more

Women Personality in Pre Independence Era

  Women Personality in Pre Independence Era Rani Velu Nachiyar(1730-1796)-  She was the first Indian queen(Sivaganga estate) to wage war with the East India Company in India. She regained her kingdom after defeating EICo. with the help of Hyder Ali and many mores. In Tamil she is regarded as Veeramangai .  She was a scholar of French, English, and Urdu languages. Savitribai Phule(1831-1897)-  She raised her voice against caste and gender discrimination. In 1848 she started school in Pune for girl education. She died while serving the Plague affected people.  Pandita Ramabai Sarasvati(1858-1922)-  1st woman to be awarded the titles of Pandita as a Sanskrit scholar and Sarasvati after being examined by the faculty of the University of Calcutta. In 1882, she presented the issue of women education to Hunter Commission . She founded Arya Mahila Samaj(Pune, 1882) . In the same year she wrote Stri Dharma Niti(Morals for Women) book and in 1883 she moved to Britain where she embraced Christia
Post a Comment
Read more

Surveys in India

  Surveys in India 1. National Family Health Survey 2020-21(NFHS-5) Year 2023 Sex ratio- 1020 Rural sex ratio- 1037 Urban sex ratio- 985 State having highest sex ratio- Kerala(sex ratio- 1084)  Sex ratio at birth- 933 4 types of sex ratios according to the stages of development. Primary Sex Ratio- Sex ratio at Fertilization Secondary Sex Ratio- Sex ratio at Birth  Tertiary Sex Ratio- Sex ratio at maturity Quaternary Sex Ratio- Sex ratio above the age of 60 years 
Post a Comment
Read more