Space (Physics) Part-I

Total Questions: 50

41. Consider the following statements: [I.A.S. (Pre) 2005]

1. A geostationary satellite is at an approximate height of 10,000 km.

2. FM transmission of music is of very good quality because the atmospheric or man-made noises which are generally frequency variations can do little harm.

Which of the statements given above is/are correct?

Correct Answer: (b) 2 only
Solution:

Geostationary or communication satellite is located in space about 36,000 km above the equator. A single geostationary satellite is on a line of sight with about 40 percent of the earth's surface. Three such satellites each separated by 120 degrees of longitude can provide coverage of the entire planet.

A major advantage of FM (Frequency Modulation) in a communication system is the possibility of improved signal-to-noise ratio (SRN or S/N) compared to AM (Amplitude Modulation).

Additional techniques, such as pre-emphasis of higher audio frequencies with the corresponding de-emphasis in the receiver, one generally used to improve overall SNR in FM circuits. Since FM signals have constant amplitude, FM receivers normally have limiters that remove AM noise, further improving SNR.

42. The satellite used for telecommunication relay are kept in a geostationary orbit. A satellite is said to be in such an orbit when [I.A.S. (Pre) 2011]

1. The orbit is geosynchronous.

2. The orbit is circular.

3. The orbit lies in the plane of the Earth's equator.

4. The orbit is at an altitude of 22,236 km.

Select the correct answer using the codes given below

Correct Answer: (a) 1, 2 and 3
Solution:

A geostationary orbit is a circular orbit, 35,786 kilometres (22,236 mi.) above the Earth's equator. Sometimes it is also known as Clark's orbit. A satellite in a geostationary orbit appears to remain in the same spot in the sky all the time. It is also referred as a geosynchronous equatorial orbit (GEO).

43. What is the geostatic position? [U.P.P.C.S. (Mains) 2005]

Correct Answer: (c) When the object moves around the Earth with the velocity commensurate with the velocity of the Earth such that it maintain a fixed position in relation to some place on the Earth.
Solution:

When the object moves around the Earth with the velocity commensurate with the velocity of the Earth such that it maintain a fixed position (fixed height) in relation to some place on the Earth, it is called geostatic position. All the geostationary satellites works on the same principle.

44. Geo-stationary satellite revolves at: [Chhattisgarh P.C.S. (Pre) 2018]

Correct Answer: (b) At fixed height
Solution:

When the object moves around the Earth with the velocity commensurate with the velocity of the Earth such that it maintain a fixed position (fixed height) in relation to some place on the Earth, it is called geostatic position. All the geostationary satellites works on the same principle.

45. In which atmospheric layer, the communication satellites are located? [U.P.P.C.S. (Mains) 2004]

Correct Answer: (d) Exosphere
Solution:

The exosphere is the outer most layer of Earth's atmosphere. Air in the Exosphere is extremely thin in many ways. It is almost the same as the airless void of outer space and in this, the communication satellites are located.

46. A geostationary satellite has a period of: [U.P.P.C.S. (Mains) 2010]

Correct Answer: (d) 24 hours
Solution:

The geostationary satellite has a same orbital period as the earth's rotation period i.e. 24 hours.

47. The time period of revolution of a geostationary satellite is: [U.P.R.O/A.R.O. (Mains) 2016, Uttarakhar P.C.S. (Pre) 2016]

Correct Answer: (b) 24 hours
Solution:

The geostationary satellite has a same orbital period as the earth's rotation period i.e. 24 hours.

48. Which of the following diagram represents the most accurate path of geostationary satellite in space. [I.A.S. (Pre) 1993]

Correct Answer: (a)
Solution:

Geostationary satellite has a circular path. Therefore option (a) represents the most accurate path of geostationary satellite in space.

49. NASA-U.S. space agency, has launched a telescope named Kepler to find: [U.P.P.C.S. (Mains) 2008]

Correct Answer: (d) Earth-like Planets
Solution:

Kepler was a space telescope launched by NASA to discover Earth-like planets orbiting other stars. It was launched in 2009. The initial planned lifetime for this was 3.5 years but it was expanded.

After 9 years of operation, NASA announced its retirement on 30 October, 2018. Kepler discovered more than 2600 'exoplanets'-including many that are promising places for life to exist.

50. Who is the scientist in whose honour the "Chandra X-ray telescope" has been named- [I.A.S. (Pre) 2001]

Correct Answer: (d) Subramanyan Chandrashekhar
Solution:

Chandra X-ray telescope is a space observatory launched by Columbia Space Shuttle on 23 July, 1999. The telescope is named after the Indian American-Astrophysicist Subrahmanyan Chandrasekhar.