B.E Third Semester Examination, Dec-2010
A Model Question Paper
1 (a) Describe the relationship between Cartesian and Cylindrical system.
(b) Explain the following term
i) Dot products of vector
ii) Properties of dot product
iii) Applications of dot product (8+12=20 Marks)
2 (a) State and explain Coulomb’s law of force between two point charges and mention the units of quantities in the force equation.
(b) A charge 1C is at (2,0,0). What charge must be placed at (-2,0,0) which will make y component of total E zero at the point (1, 2, 2).
(c) A circular ring of charge with radius 5m lies in z = 0 plane with centre at origin. If the ρL = 10 nC/m, find the point charge Q placed at the origin which will produce same E at the point (0, 0, 5) m. (5+6+9=20 Marks)
3 (a) What is electric flux? Explain the concept of electric flux.
(b) starting from the Gauss’s law as applied to the differential volume element, explain the concept of divergence.
(c) Show that the divergence of flux density due to point charge and uniform line charge is zero. (6+8+6=20 Marks)
4 (a) A line y = 1, z = 1 carries a uniform charge of 2 nC/m, find potential at A(5,0,1) if
i) V= 0V at (0,0,0)
ii) V=100 V at B(1,2,1)
(b) Derive the relation between E and V.
(c) Find the work done in moving a charge of +2 C from (2,0,0) m to (0,2,0)m along the straight line path joining two points, if the electric field is E = (12x ax – 4 yay) V/m. (5+10+5=20 Marks)
5 (a) State and explain Continuity equation.
(b) At the boundary between glass (ɛr= 4) and air, the lines of electric field make an angle of 40O with normal to the boundary. If electric flux density in the air is 0.25µC/m3, determine the orientation and magnitude of electric flux density in the glass. (10+10=20 Marks)
6 (a) Solve the laplace’s equation for the potential field in the homogeneous region between the two concentric conducting spheres with radii a and b, such that b>a if potential V= 0 at r= b and V=VO at r = a. And find the capacitance between the two concentric spheres. (10 Marks)
(b) State and prove Uniqueness theorem. (10 Marks)
7 (a) Write a note on Maxwell’s equation. (10 Marks)
(b) Write a short note on retarded potential. (10 marks)
8 (a) What is uniform plane wave? What is meant by transverse electromagnetic wave? (8 Marks)
(b) State Poynting’s theorem and explain its significance. (8 marks)
(c) Write a short note on dispersive media. (4 Marks)
NOTE: Don’t go through unit wise in this subject as question can come in mixed form. So read more topics.