Electrical Engineering questions for GATE, PSU recruitment and SSC JE draw from network theory, electrical machines, power systems, control systems, measurements and instrumentation, analog and digital electronics, and electromagnetic fields. Numerical answers include the formula used and the unit at each stage, which is where marks are commonly lost even when the approach is correct.
What is the primary function of a feedback control system?
Answer: A
Feedback control systems work by comparing the desired output with actual output and reducing the error between them through corrective action.
Q.2Easy
The transfer function of a system is defined as the ratio of:
Answer: B
Transfer function G(s) = Y(s)/U(s) is the ratio of Laplace transforms of output to input assuming zero initial conditions.
Q.3Easy
Which of the following represents a first-order system?
Answer: B
A first-order system has only s¹ as the highest power in the denominator. G(s) = K/(τs + 1) is the standard first-order form.
Q.4Easy
The characteristic equation of a system is s² + 4s + 3 = 0. The system is:
Answer: C
Roots are s = -1 and s = -3 (both negative). All poles are in the left half-plane, making the system stable.
Q.5Easy
In a bode plot, the magnitude is plotted on a scale of:
Answer: B
Bode plots use dB (20log₁₀|G(jω)|) for magnitude on a logarithmic scale and phase in degrees on a semi-log plot.
Q.6Easy
For a system G(s) = 1/(s(s+2)), the number of poles at origin is:
Answer: B
The system has one pole at s=0, making it Type 1. The denominator has s¹ factor representing one integration.
Q.7Easy
The settling time of a control system is defined as the time taken to:
Answer: C
Settling time is the time required for the transient to decay and response to remain within 2% (or 5%) of the steady-state value.
Q.8Easy
Which of the following is NOT a characteristic of a proportional (P) controller?
Answer: B
A proportional controller cannot eliminate steady-state error completely for step inputs in type-0 systems. An integral term is needed for zero steady-state error.
Q.9Easy
For a unity feedback system with G(s) = K/(s(s+3)(s+5)), what is the system type?
Answer: B
The system type equals the number of poles at origin. Here, there is one pole at origin (s in denominator), making it Type 1.
Q.10Easy
A second-order system has damping ratio ζ = 0.5. What is the nature of its response?
Answer: B
For ζ < 1, the system is underdamped and exhibits oscillatory response. At ζ = 0.5, there are definitely oscillations with exponential decay.
Q.11Easy
In root locus analysis, as the gain K increases from 0 to ∞, the closed-loop poles move along specific paths. Where do these paths originate?
Answer: B
The root locus starts at open-loop poles (K=0) and ends at open-loop zeros (K=∞). This is a fundamental property of root locus construction.
Q.12Easy
For the open-loop transfer function G(s)H(s) = K(s+1)/((s+2)(s+3)(s+4)), the system order is:
Answer: B
System order is determined by the highest power of 's' in the characteristic equation denominator. Here, it's (s+2)(s+3)(s+4) = s³+..., so order is 3.
Q.13Easy
In a state-space representation, if the system has 4 state variables, what is the dimension of the state vector?
Answer: C
The state vector x(t) contains all state variables. With 4 state variables, it's a 4×1 column vector, so the dimension is 4.
Q.14Easy
Which of the following transfer functions represents a Type-2 system?
Answer: A
Type of system is determined by the number of poles at origin. Option A has s² in denominator, making it Type-2
Q.15Easy
In the root locus of a system with open-loop transfer function G(s)H(s) = K(s+2)/(s(s+1)(s+3)), how many branches exist?
Answer: B
Number of root locus branches = max(number of poles, number of zeros) = max(3, 1) = 3
Q.16Easy
What is the bandwidth of a first-order system with time constant τ = 0.1 seconds?
