ELECTRICAL OBJECTIVE QUESTIONS WITH ANSWERS: Control System: Part-3 Objective Questions with Answers

Control System Objective Questions from Competitive Exams (GATE, IES)

[1] The first two rows of Routh’s tabulation of a third order equation are as follows.
s³ 2 2
s² 4 4

This means there are [GATE 2009]

(a) Two roots at s =± j and one root in right half s-plane

(b) Two roots at s =± j2 and one root in left half s- plane

(d) Two roots at s =± j and one root in left half s-plane

[2] The asymptotic approximation of the log magnitude vs frequency plot of a system containing only real poles and zeros is shown. Its transfer function is [GATE 2009]

(a) [10(s+5)]/[s(s+2)(s+25)]
(b) [1000(s+5)]/[s²(s+2)(s+25)]
(c) [100(s+5)]/[s(s+2)(s+25)]
(d) [80(s+5)]/[s²(s+2)(s+25)]

[3] The trace and determinant of a 2x2 matrix are known to be -2 and -35 respectively. Its eigen values are [GATE 2009]

(a) -30 and -5

(b) -37 and -1

(d) 17.5 and -2

[4] A Linear Time Invariant system with an impulse response h(t) produces output y(t) when input x(t) is applied. When the input x(t-τ) is applied to a system with impulse response h(t-τ), the output will be [GATE 2009]

(a) y(t)
(b) y(2(t-τ))
(c) y(t-τ)
(d) y(t-2τ)

[5] For the Y-bus matrix of a 4-bus system given in per unit, the buses having shunt elements are [GATE 2009]

(a) 3 and 4

(b) 2 and 3

(d) 1,2 and 4

[6] The unit step response of a unity feedback system with open loop transfer function G(s) = K / ((s+1)(s +2)) is shown in the figure. The value of K is [GATE 2009]

(a) 0.5

(b) 2

(d) 6

[7] For the driving point impedance function, Z(s)=[as²+7s+3]/[s²+3s+b], the circuit realization is shown below. The values of 'a' and 'b' respectively are [IES2010]

(a) 4 and 5

(b) 2 and 5

(d) 2 and 3

[8] For the following driving point impedance functions, which of the following statements is true? [IES2010]

Z1(s)=(s+2)/(s2+3s+5)

Z2(s)=(s+2)/(s2+5)

Z3(s)=(s+2)/(s2+2s+1)

Z4(s)=(s+2)(s+4)/(s+1)(s+3)

(a) Z₁is not positive real

(b) Z₁ is positive real

(d) Z₄is positive real

[9] The steady state error of a unity feedback linear system for a unit step input is 0.1. The steady state error of the same system, for a pulse input r(t) having a magnitude of 10 and a duration of one second, as shown in the figure is [GATE2011]