Advertisements
Advertisements
प्रश्न
The farthest objects in our Universe discovered by modern astronomers are so distant that light emitted by them takes billions of years to reach the Earth. These objects (known as quasars) have many puzzling features, which have not yet been satisfactorily explained. What is the distance in km of a quasar from which light takes 3.0 billion years to reach us?
Advertisements
उत्तर १
Time taken by quasar light to reach Earth = 3 billion years
= 3 × 109 years
= 3 × 109 × 365 × 24 × 60 × 60 s
Speed of light = 3 × 108 m/s
Distance between the Earth and quasar
= (3 × 108) × (3 × 109 × 365 × 24 × 60 × 60)
= 283824 × 1020 m
= 2.8 × 1022 km
उत्तर २
The time taken by light from the quasar to the observer
t = 3.0 billion years = 3.0 x 109 years As 1 ly = 9.46 x 1015 m
∴ Distance of quasar from the observer d = 3.0 x 109 x 9.46 x 1015 m
= 28.38 x 1024 m = 2.8 x 1025 m or 2.8 x 1022 km.
संबंधित प्रश्न
Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):
the number of strands of hair on your head
500 gm = ______ kilogram.
Ten millimetre makes one centimetre.
Numerical Problem.
Inian and Ezhilan argue about the light year. Inian tells that it is 9.46 × 1015 m and Ezhilan argues that it is 9.46 × 10 12 km. Who is right? Justify your answer.
Measure the yellow rectangle. It is ________ cm long.
The fencing of a square garden is 20 m in length. How long is one side of the garden?
Can you think of how to cut a postcard so that you can pass through it?
Chumki, Jhumri, and Imran need wire to make a fence.
- How much wire in all will the three need?
There are two beautiful lakes near a village. People come for boating and picnics in both the lakes. The village Panchayat is worried that with the noise of the boats the birds will stop coming. The Panchayat wants motorboats in only one lake. The other lake will be saved for the birds to make their nests.
- What is the length of the boundary of lake B in the drawing?
There are two beautiful lakes near a village. People come for boating and picnics in both the lakes. The village Panchayat is worried that with the noise of the boats the birds will stop coming. The Panchayat wants motorboats in only one lake. The other lake will be saved for the birds to make their nests.
- How many kilometers long is the actual boundary of lake A?
Length is a fundamental quantity.
What is the unit of measurements of very small lengths?
The distance between one end and the other end is called ______.
What is the unit of length?
SI unit of electric current is ______.
Larger unit for measuring time is ______.
To measure the distance of a planet from the earth, ______ method is used.
The distance of a galaxy is of the order of 1025 m. Calculate the order of magnitude of time taken by light to reach us from the galaxy.
