Annamalai University 2008-1st Year B.Sc Electronics " 530 ELECTRICITY AND MAGNETISM " ( - I ) ( PART - III - A - MAIN ) ( ) 5252 - Question Paper
12. (a) Define Peltier and Thomson co-efficients.
4
(b) Applying thermodynamics to a thermo couple
Show that
(dE \
n = T
(d2E\
IdT2/
and a = T
(c) The e.m.f. in a thermo couple, one junction of which is kept at 0C, is given by
E = at + bt2.
If
LLV
a = 10
C
End b o 0 y
40 C2
find the neutral temperature and temperature of inversion.
13. Explain Langevins theory of paramagnetism.
Name of the Candidate :
5 2 5 2 B.Sc. DEGREE EXAMINATION, 2008
(ELECTRONIC SCIENCE)
(FIRST YEAR)
(PART - III - A - MAIN)
( PAPER -1)
530. ELECTRICITY AND MAGNETISM
December ] [ Time : 3 Hours
Maximum : 100 Marks
PART - A (5 x 4 = 20)
Answer any FIVE questions.
All questions carry equal marks.
1. Define electric intensity and electric potential. Establish the relation E = - grad V.
2. Derive an expression for the energy of a charged condenser.
3. Obtain an expression for the force between two parallel current carrying conductors.
4. Write a note on thermoelectric power diagram.
5. Classify the magnetic materials.
6. What is meant by hysteresis ?
7. Derive an expresssion for the co-efficient of coupling between two coils.
8. Explain the various losses associated with a transformer.
PART-B (5x16 = 80)
Answer any FIVE questions.
All questions carry equal marks.
9. (a) Derive expression for the potential at
(i) an external point.
(ii) an internal point.
(iii) a point on the surface.
due to a uniformly charged spherical conductor.
(b) The atomic number of gold is 79 and the charge on the proton is 1-6x10_19C. Calculate the electric potential at the surface of the nucleus of the gold atom. The radius of the nucleus = 6-6 x 10_15m.
10. (a) What is the principle of a capacitor ?
(b) Derive an expression for the capacity of a cylindrical capacitor.
(c) A cable consisting of a wire 3 mm in diameter and insulated with 3 mm thickness of guttapercha ( = 4-26 ) is placed in water. Calculate the capacity for 1 km. length of the cable.
11. (a) Explain the principle of a potentiometer.
(b) How will you calibrate the given ammeter using potentiometer ?
(c) The resistance of a potentiometer wire 8 metres long is 8 ohms. A high resistance box and a 2 volt accumulator are connected in series with it. What should be the value of the resistance in the box if it is desired to have a potential drop of 1 micro - volt per mm ?
14. Describe Rayleighs method of determining the self inductance of a coil.
15. (a) Describe the theory of B.G. Also, explain
damping correction.
(b) The current sensitivity of a B.G. is 2-2 x 10-9 ampere for a deflection of 1 mm on a scale kept at a distance of 1 m. Calculate the charge sensitivity if the period of the B.G. is 6-2 seconds.
16. (a) Give the theory of oscillatory discharge
of a condenser through an inductance and a resistance.
(b) Find whether the discharge of a condenser through an inductive circuit having the values
C = 0-1 |if,
L = 10 mH,
R = 200 ohms
is oscillatory or not. If the circuit is oscillatory, Calculate its frequency.
14. Describe Rayleighs method of determining the self inductance of a coil.
15. (a) Describe the theory of B.G. Also, explain
damping correction.
(b) The current sensitivity of a B.G. is 2-2 x 10-9 ampere for a deflection of 1 mm on a scale kept at a distance of 1 m. Calculate the charge sensitivity if the period of the B.G. is 6-2 seconds.
16. (a) Give the theory of oscillatory discharge
of a condenser through an inductance and a resistance.
(b) Find whether the discharge of a condenser through an inductive circuit having the values
C = 0-1 |if,
L = 10 mH,
R = 200 ohms
is oscillatory or not. If the circuit is oscillatory, Calculate its frequency.
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| Earning: Approval pending. |
