Electromagnetics Field (3140912) MCQs

MCQs of Static Electric Fields

Showing 41 to 50 out of 96 Questions
41.
Three concentric spheres with radii 3, 4 and 5 m have uniform surface charge densities 8, -12 and ρs nC/m2 respectively. What should be value of ρs so that net flux coming out of a Gaussian sphere with radius greater than 5 will be zero ?
(a) 2.4 nC/m2
(b) 4 nC/m2
(c) 4.8 nC/m2
(d) 9.6 nC/m2
Answer:

Option (c)

42.
Charge distribution inside a sphere of radius 10 is given as ρv = 2 r nC/m3. Determine electric flux density D for a Gaussian spherical surface at r = 2.
(a) 2  ar  nC/m2
(b) 4  ar  nC/m2
(c) 8  ar  nC/m2
(d) 16  ar  nC/m2
Answer:

Option (a)

43.
Spherical surfaces at r=2 and r =4 carry uniform charge densities of 20 nC/m2 and -4 nC/m2 respectively. The D at 2 < r < 4 can be expressed as _________ .
(a) -16r2 nC/m2
(b) 16r2 nC/m2
(c) 80r2 nC/m2
(d) -80r2 nC/m2
Answer:

Option (c)

44.
Gauss theorem uses which of the following operations?
(a) Gradiant
(b) Divergence
(c) Curl
(d) Laplacian
Answer:

Option (b)

45.
Evaluate s (3 x  ax+ 2 y ay) · ds for a closed spherical surface defined by x2+y2+z2=9.
(a) 120π 
(b) 180π 
(c) 240π 
(d) 280π 
Answer:

Option (b)

46.
Three coaxial cylindrical sheets are present in free space with radius 2, 4 and 6 m. Each surface has uniform surface charge densities of 2 nC/m2, -4 nC/m2 and 6 nC/m2 respectively. Magnitude of electric flux density (in nC/m2) for Gaussian cylindrical surface with r = 1.
(a) 0
(b) 2.5
(c) - 4.6
(d) 8.2
Answer:

Option (a)

47.
Three coaxial cylindrical sheets are present in free space with radius 2, 4 and 6 m. Each surface has uniform surface charge densities of 2 nC/m2, -4 nC/m2 and 6 nC/m2 respectively. Magnitude of electric flux density (in nC/m2) for Gaussian cylindrical surface with 2< r <4 will be ________.
(a) 0
(b) 2/r
(c) 4/r
(d) 8/r
Answer:

Option (c)

48.
Three coaxial cylindrical sheets are present in free space with radius 2, 4 and 6 m. Each surface has uniform surface charge densities of 2 nC/m2, -4 nC/m2 and 6 nC/m2 respectively. Magnitude of electric flux density (in nC/m2) for Gaussian cylindrical surface with 4 < r < 6 will be ________.
(a) 0
(b) -4/r
(c) -8/r
(d) -12/r
Answer:

Option (d)

49.
With Gauss law as reference which of the following law can be derived?
(a) Ampere law
(b) Faraday’s law
(c) Coulomb’s law
(d) Ohm’s law
Answer:

Option (c)

50.
Evaluate s (3 r  ar+ 2 z az) · ds for a closed cylindrical surface with r = 2 m and 0 < z < 4 m.
(a) 8π
(b) 16π
(c) 96π
(d) 128π
Answer:

Option (d)

Showing 41 to 50 out of 96 Questions