Sunday, 3 May 2015

Electromagnetic Theory and Transmission Lines questions and answers

Electromagnetic Theory and Transmission Lines questions and answers


Unit-I: Electrostatics-I

Section-I: Multiple choice questions

1. The divergence theorem [d ]
a) Relates a line integral to a surface integral. 
b) holds for specific vector fields only.
c) Works for open surfaces. d) Relates a surface integral to a volume integral.

2. which one of the following is not Maxwell equation? [ d ]

3. Which of the following is zero? [ c]
a)grad div b)curl grad c)div grad d)curl curl

4. The field intensity due to a point charge Q at a distance, R, is E1. If charge is increased to ‘4Q’ and distance is increased to ‘2R’, the field intensity E2 becomes [a ]
(a) E2 = E1 (b) E2 = 4E1 (c) E2 = 2E1 (d) E2 = E1/2

5. Electrostatic field being conservative doe s not mean [ c ]
(a) Its circulation is identically zero (b) the work done in side a closed path inside the field is zero
(c) The potential difference between any two point s is zero (d) it is the gradient of a scalar potential

6. A charge Q is uniformly distributed in a sphere of radius a1 the charge density, if the same charge Q is made to occupy a sphere of radius a2=a1/4 is [ c ]
(a) 16 times more (b) 4 times more (c) 64 times more (d) 2 times more

Section-II: Fill in the blanks

10. If the electric flux density, D and electric field intensity, E are not in the same direction, the material is called as Anisotropic medium

11. Value of permeability of free space is 4π ×10^-7 H/ m.

12. According to Gauss’s law electrical flux due to any closed surface is equal to the charge enclosed by the surface.

13. Point charges 30 nC , – 20nC and 10 nC are located at (-1,0, 2) , (0,0, 0) and (1,5,-1) respectively. The total flux leaving a cube of side 6m centered at the origin is 10NC..


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