# Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-7

91. In parallel L-C circuit, at the resonant frequency

a) A line current is maximum
b) The total impedance is maximum
c) The total impedance is maximum
d) The inductive branch current is maximum

Ans: (c)

92. The series and parallel resonance in L-C circuit differs in that

a) Series resonance needs a high-resistance source for sharp rise in current
b) Series resonance needs a low-resistance source for sharp rise in current
c) Parallel resonance needs a low-resistance source for a sharp increase in impedance
d) Parallel resonance needs a low-resistance source for a sharp rise in line current

Ans: (b)

93. In a series L-C circuit at the resonant frequency the

a) Current is minimum
b) Voltage across C is minimum
c) Impedance is maximum
d) Current is maximum

Ans: (d)

94. A ferrite core has less eddy-current loss than an iron core because ferrites have

a) Low resistance
b) High resistance
c) Low permeability
d) High hysteresis

Ans: (b)

95. A coil with large distributed capacitance has a

a) High resonant frequency
b) Low resonant frequency
c) High Q
d) Low a.c. resistance

Ans: ()

96. A capacitor with power factor of 0.002 has a Q of

a) 0.002
b) 20
c) 200
d) 500

Ans: ()

97. A permalloy enclosure is the best shield against a

a) Static change
c) Varying magnetic field
d) Stray capacitance

Ans: ()

98. With stray capacitance of 10μF, the capacitive reactance at 160 MHz equals

a) 10 ohms
b) 160 ohms
c) 100 ohms
d) 1000 ohms

Ans: (c)

99. The intrinsic impedance of free space is

a) 500 ohms
b) 750 ohms
c) 637 ohms
d) 377 ohms

Ans: (d)

100.The dissipation factor of a good dielectric is of the order of

a) 0.02
b) 0.002
c) 0.2
d) 0.0002

Ans: (d)

101. The dissipation factor of a good dielectric is practically same as power factor of the dielectric.

a) True
b) False

Ans: (a)

102. The velocity of propagation of an electromagnetic wave is given by

a) √LC
b) √(L/C)
c) √(1/LC)
d) 1/√LC

Ans: (d)

103. The total electric flux through any closed surface surrounding charges is equal to the amount of charge enclosed. The above illustration is known as

a) Maxwell’s First Law
b) Maxwell’s Second Law
c) Gauss’s Law
d) Coulomb’s Square Law

Ans: (c)

104. The magnetic flux density B is analogous to

a) Electromotive force V
b) Displacement current D
c) Electric intensity
d) Electric displacement

Ans: (c)

105. Which of the following is the continuity equation ?

a) ∂p/∂t = div i
b) curl H = 𝒊
c) div D = P
d) div i = 0

Ans: (a)

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