USN
ffiffi 18EC55
Fifth Semester B.E. Degree Examination, Dec.2024lJ an,2025
Electromagnetic Wave
'l'ime: 3 hrs. Max. Marks: 100
Note: Answer any FIVE full questionsl choosing ONE full question fram each module.
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Module-1
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la. State and explain Coulomb's law in vector form. (10 Marks)
,1 b. If D= xy2z'a*+x'yz'ay+xzyz zd,c/m2 find i) an expression for p, ii) the total change
= within the cube defined by0 S x<2;0 < y< 2 ;0 <z<2. (10 Marks)
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a-.- a. Obtain an expression for electric field intensity due to infinite line charge. (10 Marks)
b. Define the following terms in electric field density i) Line charge ii) Surface charge
iii) volume charge.
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-c (10 Marks)
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Nlodule-2
3a. State and prove Gauss law for po.int charge. (05 Marks)
-u b. State and prove divergence theorem. (05 Marks)
Give the electrical tube density D : 0.31 a,nc/ mz in free space.
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i) Itrind E at Pt. P(r :2 ;0 :25o ; $ : 90').
ii) Find the total change within *re sphere r: 3
iii) Find the total electric flux leaving the sphere r: 4. (10 Marks)
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/N
OR
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4 a. Obtain an expression for integral form of work done in raloving a Pt. Charge Q from one
3o position to another position. (08 Marks)
,c
a, b. Calculate the work done in moving a 4C charge from B(1, 0, 0) to A(0,2,0) along the path
)D
A-
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y=2-2x,2:0inthefieldE:(1)5a-V/M (2)5x a.V/m (06Marks)
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c. A 15 nc point charges ps at the origin in free space. Calculate V1 if point P is located at
P(-2,3, -l) and \/:0 at (6,5,4). (o6Marks)
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Module-3
5 a. Drive the Poisson's and Laplaces equations. (08 Marks)
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b. State the prgvg the Stoke's theorem. (06 Marks)
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c. LetV:2xfz3 andE:EsgivenpointP(l ,2,-l).Calculate i)VatP ii)EatP iii)p,atP.
(06 Marks)
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o 6 a. State and prove the Amperes circuital law. (05 Marks)
'./. b. l)rive the expression for vector magnetic potential. (06 Marks)
= c. A current elernent ldl- : 10-'(2 a* I 4ay - a,) Nm located at A(-5, 3 -2) produces a
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o.
field dH at B(3, -4, 3) i) Give a unit vector in the direction at dH at B ii) Find d(H) at B.
E (08 Marks)
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18EC55
Module-4
a. Derive an expression for the Force between differential current elements in magnetic field.
(06 Marks)
b. The field B : - 2a* +3a, + 4a,mT is oresent in free space. Find the vector florce excrted on a
st. wire carrying 12.{ current in the aae direction given A(1, 1, 1) and B(2, i, l).
(08 Vrarks)
c. An air core toroid has 500 tums mean radius of 15 cm cross sectional area oi'6 cm-.
The magnetic motive force is 2000 AT. Calculate total reluctance flux, flux density, ficld
intensity inside the core. (06 Marks)
OR
a. Write note on forces on magnetig materials. (10 Marks)
b. Write a note on magnetic eireuits. (10 Marks)
Module-5
a. Drive the expresglon for a stationu.V .,fot"a puth in a time varyiiig field statically irrclucccl
EMF. (o6 rllarks)
b. State Maxwell's equation in both point form and in integral form. (06 Marks)
c. Find the frequency at which conduction current density and displacement current density arc
equalinamediumwitho:2x l}a and e,= 81. (08 Marks)
OR
10 a. State and explain poynting theorem. (08 Marks)
b. Define the following terms in uniform plane wave i) phase velocity ii) Intririsic impedancc
iii) wave length, (06 l\la rks)
c. The depth at penetration in a certain conducting medium is 0.1 m and the frequcllcy of thc
electromagnetic wave is I.0 MHz. Find the conductivity of the conducting nrcdiurn.
(06 Marks)
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