LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034 B.Sc. DEGREE EXAMINATION – PHYSICS V SEMESTER – NOVEMBER 2003 PH 5400 / PHY 400 – GEO PHYSICS   07. 11. 03                                                                                                 Max.  : 100 Marks 1.00 – 4.00.

 

PART–A

 

Answer All questions                                                                               (10 x 2 = 20 marks)

 

1. What is a P – wave? What is it’s velocity?
2. State the generalised form of Snell’s law, with a ray diagram.
3. Distinguish between surface waves and body waves with respect to their intensity variation with distances

 

4. What are the quantities that can be measured using a Seismometer?
5. Bring out the difference between focus and epicentre of an earth-
6. Write down the Laplace’s and the Poisson’s equation obeyed by the gravitational potential.

 

7. What is the cause of the main (magnetic) field of the earth according to the dynamo theory?

 

8. Explain briefly, the Gauss method of determining the earth’s magnetic field
9. Give the decay schemes of the radio nuclide K⁴⁰.
10. List the two possible sources of heat within the Earth.

 

PART–B

 

Answer any FOUR questions                                                               (4 x 7 ½ = 30 marks)

 

11. Calculate the bulk modulus and the shear modulus of a material having the following properties.

Density  =  4000 kg / m³;  dilatational  velocity (a) = 10 km / s and        shear velocity (b) = 6 km / s.

 

12. Outline the principle and the construction of the strain seismograph with a simple
13. a) State the relation between the energy released and the magnitude of an earth-quake
14. b) Compare the energies released in earth quakes of magnitudes M = 6 and M = 2.

-2-

 

14. Explain the dynamo theory of earth’s magnetism with the help of the Faraday disc generator.

 

15. Obtain an expression for the variation of temperature with depth below the surface of the earth.

PART–C

 

 

Answer any FOUR questions                                                             (4 x 12 ½ = 50 marks)

 

16. a) Find an expression for the time of travel of a seismic wave due to refraction in the

outer layers of earth                                                                                   (6 ½ mark)

 

1. b) Derive an expression for the gradient of density in terms of velocities of body

waves                                                                                                             (6 mark)

 

17. Discuss the theory of a horizontal seismograph with a neat diagram and explain all

possible cases.

18. Explain the working of (I) Hammond and Faller method (of measuring gravity) and
19. ii) Worden gravimeter, with neat diagrams                                  (6 + 6 ½)

 

19. Explain the theory of (I) Saturation magnetometer and (ii) alkali vapor

magnetometer.                                                                                                   (5 + 7 ½)

20. Give the theory of radioactive dating of rocks and minerals using (i) the decay

scheme of Rb⁸⁷ and (ii) the decay scheme of K⁴⁰ .

 

 

 

 

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  LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

SC 14

B.Sc.  DEGREE EXAMINATION –PHYSICS

FIFTH SEMESTER – APRIL 2007

PH 5400 – GEO PHYSICS

 

 

Date & Time: 30/04/2007 / 1:00 – 4:00     Dept. No.                                                     Max. : 100 Marks

 

 

PART –  A                  10×2=20 marks

Answer ALL  questions.

1. How can one seismically distinguish between an earth quake and a large explosion?
2. What is the implication of a shadow zone in the internal structure of the earth?
3. Distinguish between Rayleigh and Love seismic surface waves.
4. Give the significant differences between the body wave and the surface wave.
5. Define the term focus and epicentre.
6. Write down the Laplace’s and Poisson’s equation obeyed by the gravitational potential.
7. Explain briefly the Gauss method of determining the earth’s magnetic field.
8. Write a note on geological time scale.
9. List the two possible sources of heat with in the earth.
10. How are the ages of rocks determined?

PART – B

Answer any FOUR questions.                                                     4×7.5=30 marks

1. What are P and S waves? Describe the method by which the epicentre of an earthquake is located.
2. Outline the principle and construction of the strain seismograph.
3. Write a brief account of the magnitude and occurance of earthquakes.
4. Explain the dynamo theory of Earth’s magnetism with the help of the Faraday disc generator.
5. Discuss the variation of temperature with in the earth.

PART-C                                                                                                                                        Answer any FOUR questions.                                               4×12.5=50 marks

1. Discuss the analogy between an optic wave and a seismic wave interms of reflection and refraction phenomenon.
2. Discuss the theory of horizontal seismograph with a neat diagram and explain all possible cases.
3. Explain the working of a) Hammond and Faller method of measuring gravity and    b) Worden gravity meter with neat diagram.
4. Explain the theory of a) saturation magnetometer and b) Alkali vapour magnetometer.
5. Given the theory of radioactive dating of rocks and minerals using a) the decay scheme of R_b⁸⁷ and b)the decay scheme of K^40.____________________

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – PHYSICS

FG 18

FIFTH SEMESTER – APRIL 2008

PH 5400 – GEO PHYSICS

 

 

 

Date : 03/05/2008                Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

 

PART-A                                                     10 X 2 = 20

Answer all questions

 

1. What is meant by phases in seismic waves?
2. What is a shadow zone?
3. Give the significant differences between body wave and surface wave.
4. Express Adams and Williamson equation for the variation of density with depth.
5. Define the terms epicenter and focus of an earthquake.
6. Write down the Laplace’s and Poisson’s equation obeyed by the gravitational potential.
7. Explain briefly the Gauss method of determining the earth’s magnetic field.
8. What are the prediction for the composition of the core from shock wave measurements?
9. Give the decay schemes of the radio nuclide K⁴⁰.

10 .List the two possible sources of heat within the earth.

 

 

PART-B                                                                4 X 7.5 = 30

Answer any four questions

 

11. What are P and S waves? Describe the method by which the epicenter of an earthquake is located.
12. Outline the principle and construction of the strain seismograph.
13. Give an account of the Richter Scale of magnitude for earthquakes.
14. Describe the quantitative investigation for an equation of state of the mantle
15. Discuss the variation of temperature within the earth.

 

 

PART-C                                                            4 X 12.5 = 50

Answer any four questions

 

16. Discuss the analogy between an optic wave and a seismic wave in terms of reflection

and refraction phenomenon.

17. Obtain the Seismograph equation for a horizontal seismograph and deduce the two

types of instrumentation that follows the equation.

18. Explain the working of i)Hammond and Faller method (of measuring gravity) and

ii)Worden gravitymeter with neat diagrams.(6+6.5)

19. Explain the theory of i)saturation magnetometer and ii)Alkali vapour magnetometer(5+7.5)
20. a) Discuss the flow of heat to the surface of the earth from the core.
21. b) Discuss the source of heat within the earth.

 

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