Instructions for Formatting Your Assignment

Dear Student,

We hope you are familiar with the system of evaluation to be followed for the Bachelor’s Degree Programme. At this stage you may probably like to re-read the section on assignments for Elective Courses in the Programme Guide that we sent you after your enrolment. A weightage of 30 per cent, as you are aware, has been earmarked for continuous evaluation which would consist of one tutor-marked assignment (TMA) for this course.

Instructions for Formatting Your Assignment

Before attempting the assignment please read the following instructions carefully:

1)On top of the first page of your TMA answer sheet, please write the details exactly in the following format:

ENROLMENT NO.:……………………………………………

NAME :……………………………………………

ADDRESS :……………………………………………

……………………………………………

COURSE CODE: …………………………….

COURSE TITLE : …………………………….

ASSIGNMENT NO. ………………………….…

STUDY CENTRE: ………………………..….. DATE:.…………………………………...

PLEASE FOLLOW THE ABOVE FORMAT STRICTLY TO FACILITATE EVALUATION AND TO AVOID DELAY.

2)Use only foolscap size writing paper (but not of very thin variety) for writing your answers.

3)Leave 4 cm margin on the left, top and bottom of your answer sheet.

4)Your answers should be precise.

5)While solving problems, clearly indicate the question number along with the part being solved. Be precise. Write units at each step of your calculations as done in the text because marks will be deducted for such mistakes. Take care of significant digits in your work. Recheck your work before submitting it.

6)This assignment will remain valid for one year from January 01, 2009 to December 31, 2009.

7)A feedback form is being sent along with this assignment. PLEASE FILL IT UP AND POST IT TO US.

We strongly feel that you should retain a copy of your assignment response to avoid any unforeseen situation and append, if possible, a photocopy of this booklet with your response.

We wish you good luck.

Tutor Marked Assignment

Astronomy and Astrophysics (PHE-15)

Course Code: PHE-15

Assignment Code: PHE-15/TMA/2009

Max. Marks: 100

Note:The marks for each question are indicated against it. Symbols have their usual meanings.

1. (a) The distance of planet Jupiter from the Sun is 5 AU. Express this distance in light year and parsec. (5)

(b) Calculate the ratio of the surface temperatures of the stars 1 and 2 from the following data:

Star Absolute magnitude Radius (R)

1 2 64

2 7 4 (5)

2.(a) Show the horizon coordinates of a star X on a celestial sphere for a location at latitude 30 N. Would these coordinates be the same at latitude 45 N? (4+1)

(b) Why do X-ray telescopes need to be placedbeyond the Earth’s atmosphere? Which telescope, optical or X-ray, would have higher resolving power for the same aperture? Calculate the magnitude of the faintest object that a 10 m optical telescope can detect.

(1+1+3)

3.(a) A main sequence star has mass 2×1031 kg and radius 3×109 m. Obtain an estimate of the average temperature throughout the star. Examine if Newton’s theory would be adequate for the study of this star. (3 + 2)

(b) Explain how sunspots survive for so long even though they are surrounded by hotter matter. (5)

4. (a) The mean distance of Mars from the Earth is 0.5 A.U. and its orbital period is 687 days. Calculate the orbital period of Jupiter given that its mean distance from the Earth is 4 A.U. (5)

(b)A star has surface temperature of 25000 K. Which lines would be prominent in its spectrum and why? (1+4)

5.(a)Derive the expression for the mean temperature in a star:

Will this result apply to a star which is not in equilibrium?(4+1)

(b) The mean free path of photons in stars is of the order of 0.2 cm. Show that the time taken for a photon to reach the surface of a star of radius 4 R is of the order of one million year. (5)

6. (a) Describe the composition of the interstellar medium. Explain how it has been possible to map the HI clouds. (2+3)

(b) Write down the condition under which a large molecular cloud collapses to give rise to new stars. Calculate the time of free fall of an HI cloud of density 106 particles / m3 if the collapse is adiabatic. (1+4)

7. (a) Explain the meaning of a degenerate gas. A white dwarf star has a mass of 1030 kg. Its luminosity is 1024 Js−1. Calculate how long it can survive with its present luminosity if its internal temperature is 107 K. (2+3)

(b)How long will a 5Mstar burn hydrogen as fuel, given that the Sun will do so for about
1010 years? (5)

8. (a) Obtain an expression for the radial velocity of objects in the galaxy as a function of their galactic longitude. (5)

(b) Distinguish between an active galaxy and a normal galaxy. Describe the classification of active galaxies. (2+3)

9.(a) Describe Hubble’s Classification scheme for galaxies. How bright were the galaxies which were included in the classification scheme? (4+1)

(b) An electron is moving with a speed of 0.9c in a magnetic field of strength 106 G. Calculate the peak frequency at which the electron will radiate. (5)

10. (a) What is cosmic background radiation? Explain why it is so important to the debate between and evolving and a steady-state universe. (2+3)

(b) If the temperature of the background radiation today is 3 K, at what time after the birth of the universe was the temperature 1015 K. Take the age of the universe as 15×109 years. (5)

TENTATIVE SCHEDULE FOR PHYSICS PROGRAMMES BROADCAST ON GYAN DARSHAN 1

January 2009 – May 2009

This is the tentative schedule for Physics students. The students may approach their cable operator to avail this facility.

Date/Day / Time Slot / Course Code / Video Programme Title
January 2009
11-0109
(SUN) / 9.00–9.30 pm / PHE-01 / Exploring Physics: Experiment with Low Cost Materials
PHE-01 / The Bicycle: A Vehicle for Teaching Physics
18-01-09
(SUN) / 9.00–9.30 pm / PHE-02 / Simple Harmonic Motion
27-01-09
(Tues) / 8.15–9.00 am / PHE-06 / Applications of the First Law of Thermodynamics
25-01-09
(SUN) / 9.00–9.30 pm / PHE-15 / Exploring the night sky
February 2009
15-02-09
(SUN) / 9.00–9.30 pm / PHE-15 / On the Trail of Stars
17-02-09
(Tues) / 8.15–9.00 am / PHE-06 / Second law of Thermodynamics
24-02-09
(Tues) / 8.15–9.00 am / PHE-02 / Coupled Oscillations
March 2009
10-03-09
(Tues) / 8.15–9.00 am / PHE- 13 / Introduction to Crystal Structure
17-03-09
(Tues) / 8.15–9.00 am / PHE- 15 / Astronomical Coordinates
22-03-09
(SUN) / 9.00–9.30 pm / PHE- 02 / Dolan
24-03-09
(Tues) / 8.15–9.00 am / PHE- 06 / Carnot Cycle
April 2009
12-04-09
(SUN) / 9-00-9.30 pm / PHE- 15 / Glimpses of the Cosmos
19-04-09
(SUN) / 9-00-9.30 pm / PHE- 01 / Rotating Frames of Reference
May 2009
19-05-09
(Tues) / 9-00-9.30 pm / PHE -15 / On the Trail of Stars
17-05-09
(SUN) / 9.00-9.30 pm / PHE -15 / Astronomical Coordinates

TENTATIVE SCHEDULE FOR EDUSAT/TELECONFERENCING SESSIONS AT STUDY CENTRES

JANUARY 2009 TO MAY 2009

Time: 5.00to 5.45 pm and 6.00 to 6.45 pm

Month/Date* / Course
January 2009
23-01-09 / PHE-11
February 2009
27-02-09 / PHE-13
March 2009
27-03-09 / PHE-02
April 2009
24-04-09 / PHE-14
May 2009
22-05-09 / PHE-09

*Fourth Friday of every month

TENTATIVE SCHEDULE FOR PHYSICS STUDENTS ON DD1 (National Network)

JANUARY 2009 TO MAY 2009

Time: 6.00 AM to 6.30 AM

Month/Date* / Course / Topic
January 2009
12-01-09 / PHE-13 / Introduction to Crystal Structure
February 2009
09-02-09 / PHE-01 / Ghurni Nirdesh Tantra (Hindi)
March 2009
09-03-09 / PHE-15 / Astronomical Coordinates
April 2009
13-04-09 / PHE-06 / Ushmagatiki ke Anuprayog
May 2009
11-05-09 / PHE-15 / On the Trail of Stars

*Second Monday of every month

Dear Student,

We would like to get your feedback on the courseAstronomy and Astrophysics(PHE-15) while you are studying it. Fill in your answers about each unit while you are studying/revising it.

THIS FEEDBACK IS COMPULSORY AND YOU MUST SEND IT TO USas without the feedback your assignment will be considered incomplete. Please keep a copy of your assignment with you for the sake of record.

Do not give incorrect information just to please us. Your answers should be based on your own experience, good or bad; pleasant or otherwise.

PLEASE POST YOUR FEEDBACK AND THE ASSIGNMENT RESPONSE OF PHE-15 TO THE FOLLOWING ADDRESS:

Prof. Vijayshri

Course Coordinator, PHE –15

School of Sciences, IGNOU

Room no. 128, Raman Block,

New Academic Complex

Maidan Garhi

NEW DELHI 110068

If you face any difficulty regarding the course, please feel free to contact us on our e-mails: ,.

We wish you all the very best.

(Vijayshri)

FEEDBACK ON “ASTRONOMY AND ASTROPHYSICS” (PHE-15)

Tick () the appropriate responses, wherever needed.

a. Name : …………………………………… b. Male / Female

c. Enrolment Number: ………………………. d. Date of birth : ………………

e. Study Centre Code and Name .…………………………...

Do you have access to Internet? At home / Yes, at a friend’s home / Yes, at cyber café / Yes, at study centre / No

If yes, write your e-mail address: ......

3. Are you doing B.Sc. Major in Physics? Yes/No.

a)If not, please list the Physics electives you have opted for in B.Sc.

………………………………………………………………………………………………………………………………………………………………………………

4. List the electives that you have taken from other disciplines.

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

5.Rate your proficiency in English:Very good/ good/ fair/ average/ not so good

6.Are you employed?Yes/No.

If yes, please specify the nature of the employment

………………………………………………………………………………………………………………………………………………………………………………………………

7.Did you study the course introduction and block introductions before studying the units.

Yes/No.

a)If yes, do you have any suggestions about their content, length, language, etc.

………………………………………………………………………………………………………………………………………………………………………………

………………………………………………………………………………………

8.Did you read the introduction and objectives of each Unit before studying it?Yes/No.

9.Are the introduction and objectives of the Units clear to you?Yes/No.

If not, specify the difficulties:

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

10.Put a tick mark on the correct response:

(i) / The level of the course was as I expected. / Yes/No, it was too high/ No, it was lower.
(ii) / The topics, concepts covered were interesting and informative. / Yes /No
(iii) / The mathematics used was as I expected. / Yes/No, it was Difficult/No, it was easy
(iv) / I would have preferred a non-mathematical explanation. / Yes /No

11.Would you like:

(i) / to attend radio counseling for the course? / Yes /No
If yes, please mention the preferred timings
(ii) / to attend teleconferencing for the course? / Yes /No
If yes, please mention the preferred timings.
(iii) / your difficulties to be solved through letters from counsellors. / Yes /No
(iv) / to use the INTERNET facilities for counseling. / Yes /No

12.Do you use computer for study purpose? Yes/No

If yes, which software packages do you use?

13.Your overall comments on the course. (Write the comments on the course after studying it.) You may use extra pages.

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

14. Please fill the enclosed annexure to give us unit-wise feedback.

15.If you have filled in words like 'not clear/difficult/not sufficient/not interesting', etc. in any of the rows and columns for the units in Annexure, please mention what is not clear about each part. Use additional pages if need be.

16.What (e.g., explanation, diagram, examples, definitions, etc.) would you like to be added or deleted in the units to make it easier to study? Use additional pages if your answer is long.

Have you received teaching comments from counsellors on your TMA responses for other physics electives that can help you in learning the concepts better? Yes/No

If yes, please list all such TMAs.

ANNEXURE

4. Unit wise Feedback : Answer this part while studying each unit or immediately afterwards.

Note :Please tell us about your difficulties in studying each section of the units. To describe your response, you may select the appropriate words from among the following : not clear, not sufficient, difficult, not relevant, not interesting. If you wish, you can use any other words. For example, if you feel that the language used in Sec. 1.2 is difficult and not clear, you should write the words ‘difficult, not clear’ at *. In the last column, you have to tell the approximate time you have taken to study each section.

Block 1 Unit 1 : Astronomical Scales

Section / Explanation of Concepts / Examples
given / Language
used / Mathematics
used / Technical
Definitions / Figures and Tables / SAQs and Terminal Questions / Time taken to study the section (min./h.)
1.2 / *
1.3
1.4
1.4.1
1.4.2
1.4.3
1.4.4

Instructions for Formatting Your Assignment