Circuit & Field Theory - MCQs from AMIE exams (Summer 2017)

1. A wedge is described by z = 0, 30° < ⲫ < 60°. Which of the following is incorrect?
(a) The wedge lies in the x - y plane.
(b) It is infinitely long.
(c) On the wedge, 0 < ρ < ∞
(d) A unit normal to the wedge is ± az
(c) The wedge includes neither the x-axis nor the y-axis.

2. Given field A̅ = 3x2yza̅x + x3za̅y + (x3y - 2z)a̅z it can be said that A̅ is.
(a) Harmonic
(b) Divergenceless
(c) Solenoidal
(d) Conservative

3. If ∇.D̅ = ∈∇.E̅ and ∇∇.J̅ = σ∇.E̅  in a given material, the material is said to be
(a) Isotropic
(b) Linear
(c) Homogenous
(d) Linear and homogenous.

4. One of these equations is not Maxwell’s equation for a static electromagnetic field in a linear homogeneous medium.
(a) ∇2A̅ = μ0J̅
(b) ∇.B̅ = 0
(c) ∇ x D̅ = 0
(d) ∮B̅.dl̅ = μ0I̅

5. When a sinusoidal voltage is suddenly applied to an electrical circuit which of the following constitutes its response?
(a) Steady-state only
(b) Forced only
(c) Transient only
(d) Transient and forced.

6. Which of the following is essential for the reciprocity theorem to be applicable?
(a) Linearity
(b) Bilateralism
(c) No initial history
(d) All of these

7. A charge Q is uniformly distributed throughout a sphere of radius a. Taking the potential at infinity is zero, the potential at r = b < a is
(a) - \int_\infty ^b {\frac{{Qr}}{{4\pi { \in _0}{a^3}}}dr}
(b) - \int_\infty ^b {\frac{Q}{{4\pi { \in _0}{r^2}}}dr}
(c) \int_\infty ^a {\frac{Q}{{4\pi { \in _0}{r^2}}}dr} - \int_a^b {\frac{{Qr}}{{4\pi { \in _0}{a^3}}}dr}
(d) \int_\infty ^a {\frac{Q}{{4\pi { \in _0}{r^2}}}dr}


Answers

1. (b)

2. (d) 
Hence, conservative.

3. (d)

4. (a) Maxwell equations are

In simpler forms, these are


5. (c) Transient Response of Control System: As the name suggests transient response of control system means changing so, this occurs mainly after two conditions and these two conditions are written as follows-
  • Just after switching ‘on’ the system that means at the time of application of an input signal to the system.
  • Just after any abnormal conditions. Abnormal conditions may include a sudden change in the load, short-circuiting etc.
6. (d) The network should be bilateral linear and time-invariant.

7. (a)

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